Michelle Rounds, who was diagnosed with aggressive fibromatoses earlier this year (12), originally began suffering with a mysterious illness on 13 May (12), America's Mother's Day.
Overcome by pain, she dropped to the floor and started shaking, and the A League of Their Own star confesses their four children feared they were about to watch their step-mum die right before their very eyes.
She tells the New York Daily News, "I do think Michelle's illness was scarier to the kids because it was more visible and it lasted the whole summer.
"She first got sick on Mother's Day and she was in excruciating pain, shaking and convulsing on the floor in a fetal position. Doctors didn't know what was wrong with her. The kids would ask, 'Is she going to die?'"
Rounds eventually underwent surgery to have rare cancer-like desmoid tumours removed in June (12) and she is now well on her road to recovery.
O'Donnell wed Rounds in secret back in June (12), just weeks before her partner began her first round of surgery.