The Charlie's Angels icon lost her battle with cancer in 2009. Her and O'Neal's troubled son Redmond missed the actress' final days as he was in jail for drug offences.
He's since sought treatment for his addictions and graduated from an intensive drug program last summer (Aug10), but the 26 year old is still struggling to come to terms with his mother's death.
The Love Story star openly sobbed as he appeared on Piers Morgan Tonight and detailed his son's desire to be reunited with Fawcett.
O'Neal says, "Farrah was a very strong presence in my life. She permeated my mind and my being. She had that kind of hold on me.
"I had somebody that I loved. I have a son who struggles with his life because he's tempted to join her. He's 26 and he's tempted to go because he misses her so much and he feels that he shamed himself so much. It's tricky, you know. It's crazy.
"I say to him, 'That's not what she wants. She wants you to have a wonderful life - live it for her. She doesn't want you to join her.' And he agrees, but I'm not sure he does - he just says he agrees. None of it has been resolved."
The stars began dating in the late 1970s, but Tatum became estranged from her dad after he moved in with Fawcett, and never accepted the Charlie's Angels icon into her life.
And Tatum, who was a teenager when her dad began romancing the blonde beauty, did everything she could to split the couple up.
O'Neal tells Piers Morgan Tonight, "Farrah was hopeful that Tatum and I would at least have some kind of peace, but it wasn't to be.
"Eventually she (Tatum) did (become estranged) because she was not supportive - she was cruel. She wanted it to go down, she did not see it as a love affair - she did not see it like I saw it. She didn't help me. I needed help.
"I started to feel like I should keep them apart because Tatum was saying things to her like, 'Has he beaten you yet?' I realised she was going to try and take it out her own way... So I wasn't so enthusiastic about us all together anymore because she wasn't done until it had failed. The stronger Farrah and I got, the weaker Tatum and I got. I saw it and I didn't know what to do."
Tatum alleged in her controversial autobiography A Paper Life that her father physically and mentally abused his children but Ryan denies all the accusations. The pair has since repaired its relationship.
O'Neal tells British newsman Piers Morgan he thinks the actress, who lost her battle with cancer two years ago (09), would still be alive if it wasn't for his family's long-standing feuds.
Appearing in a pre-taped episode of Piers Morgan Tonight, which aired on Monday night (20Jun11) on CNN, O'Neal said, "I just think that if she had never met us, would she still be alive today... because nobody knows what causes cancer, do they really?
"There was turmoil during my love affair with Farrah, a lot of it caused by my family - particularly Tatum."
And when a stunned Morgan said, "It's a harsh thing to say," the actor responded, "Sorry Tatum, but you probably know too."
The interview aired just a day after reality show Ryan & Tatum: The O'Neals debuted on Oprah Winfrey's OWN U.S. TV network. The series chronicles father and daughter's attempts at a reconciliation after a lengthy estrangement, which began when the actor started dating Charlie's Angels star Fawcett.
The Paper Moon star married the tennis star when she was just 22 but they divorced in 1994 after having three kids together during their eight years of marriage.
O'Neal insists they try to maintain a "civil" relationship, but it has been years since they last spoke.
She tells CNN host Piers Morgan, "We get on as well as a divorced couple who have three grown kids can. I mean, we are civil. We don't (talk regularly)... but that's OK. Not very often... My daughter just got her tonsils out, so I texted him that day. (We last spoke) maybe two years ago."
The actress, who long struggled with substance abuse, is convinced McEnroe still struggles to forgive her former drug addictions, although she has been sober for the last year.
She adds, "He's not really a fan of mine. I said I was a fan of his. I don't think he sees addiction as a disease. I think he sees it as a moral deficiency in a person. So therefore, he thinks that I really kind of went out of my way to ruin my life and drop my children. That is not the case at all. I have a lot of regret, obviously, for all the choices that I've made."
Weiner resigned from his position as a New York congressman on Thursday (16Jun11) after it emerged he had lied about sending a saucy picture of himself to a female student via Twitter. He also confessed to having intimate phone and internet conversations with at least six women outside his marriage.
O'Neal, who has a history of drug abuse and has been clean for a year, has now compared Weiner's behaviour to that of an addict.
She tells CNN host Piers Morgan, "It is really sad, because he was a really ambitious, up-and-coming congressman, who wanted to be mayor. So the idea that he self-sabotaged this hugely speaks to a definite addiction.
"Whether... he knew it was an addiction or not, I don't know. It is a complete sabotage of everything... It is almost like he had to do it, in a way, even though he's married to one of the most beautiful women in the world...
"This compulsion speaks very highly to addiction... I can imagine that the fact that he did that so recently after his marriage speaks to an incredible compulsion... That no matter what happens, he had to do it."
A spokesperson has confirmed Weiner is checking into a rehabilitation centre "to focus on becoming a better husband and healthier person", but the type of treatment has not been divulged.
The once-estranged father and daughter have attempted to work through their problems for a new reality TV show, Ryan & Tatum: The O'Neals, which begins later this month (Jun11), but both still have opposing viewpoints on why their relationship went bad.
Tatum insists she felt abandoned when her dad went to live with Fawcett, while the movie veteran claims his daughter wanted nothing to do with him.
He says, "From Tatum's standpoint, I had lost interest in my family and I had found a new interest in my life, and that appalled her. So she fled.
"I never would have imagined, I just adored her, that she'd leave me."
And in an emotionally-charged interview with U.S. news show Entertainment Tonight, O'Neal admits he would have given up Fawcett if he knew that the romance would lead to a lengthy estrangement with his daughter.
Asked if he would have chosen Tatum over Farrah, the actor says, "That's not a fair question, that's a terrible question - but I would."
By the time he realised his daughter no longer wanted anything to do with him, it was too late: "I didn't know where she was, I wish I did."
The former Frasier star has filed for primary physical custody of their six-year-old son Jude, effectively splitting him from his sister Mason, nine.
Camille, who has challenged Grammer's claim by lodging her own legal papers for sole custody of both kids, has raised fears for her children's privacy while staying at their various holiday homes and requested a judge to forbid any overnight stays by members outside of their immediate family, reports TMZ.com.
Her lawyer Neal Hersh brought the motion before a judge on Thursday (09Jun11) and he ruled in her favour, stating that any visitors had to get written consent from both Grammer and Camille.
Grammer is pushing for the custody case to go to trial.
The Something Borrowed star exchanged vows with producer Neal Dobson at the Nashville, Tennessee home of her sister Kimberly Williams-Paisley, the country singer's wife.
Williams tells People.com, "We wanted an intimate, farm-inspired wedding. We basically planned an upscale keg party!"
Gushing about her new husband, she adds, "He grounds me. He allows me to laugh at myself and calms me down. He puts things in perspective."
The Love Story star has signed a deal with Crown Archetype publishers to write his memoirs, which will explore his on/off relationship with the actress, who died in 2009.
The book, tentatively titled Past Imperfect, will also delve into O'Neal's troubled relationship with his daughter Tatum. The memoirs are due out next year (12).
The actress became embroiled in a legal fight with Aubry in December (10), when the model filed a paternity petition asking to be officially recognised as the father of two-year-old Nahla following the couple's split last year.
At the time, Berry and Aubry had not filed for child custody, visitation or support.
Berry subsequently quit a role in Garry Marshall's romantic comedy New Year's Eve, in which she was set to play Jon Bon Jovi's lover, so she could focus on the court battle.
And, during a hearing in Los Angeles on Wednesday (16Feb11), a judge ruled Berry would be able to take Nahla with her on film shoots across the U.S.
The Oscar winner's lawyer, Neal Hersh, tells TMZ.com, "We are pleased the judge took the time to deal with this very imminent and important issue. The judge read a great deal of paperwork and gave us time to argue.
"Halle is very pleased with the judge's order."
Aubry withdrew his custody petition following the ruling, but is continuing to pursue the paternity action.
As a result of the custody case, Berry has reportedly chosen to return to work on New Year's Eve, although she will play a different role after Katherine Heigl was cast as her replacement.