Actress/singer Jenifer Lewis has been secretly struggling with bipolar disorder for 24 years. The Sister Act star, 57, reveals she was diagnosed with the mental illness in 1990 after she was overcome with the unbearable grief of losing her father. She tells newsone.com, "I was overwhelmed with my grief, unable to handle my feelings. I cried and cried, and I started to scream. I wanted to be let out of the darkness." She was subsequently found to be suffering from the condition and Lewis admits coming to terms with the health crisis was the turning point in her personal battle. She explains, "It's hard to accept that you have a problem. That's another piece of the disease - the denial. You think everyone cries themselves to sleep. You should ask yourself why am I so depressed, why am I so angry with my children, angry with my partner... why am I depressed, or over the top?" Lewis has been relying on regular therapy sessions and prescription medication to help her keep the mental disorder under control and she insists life has been made a lot easier now she knows how to deal with her problems. She adds, "You have to look in the mirror... and say - before you can go or grow into anything - you have to say you love yourself."