Erica Arsenault was Dorothy's daughter-in-law for more than a decade.
"I loved her from the beginning," Dorothy told INSIDE EDITION's Paul Boyd.
Unlike a lot of brides, Arsenault never considered Dorothy to be the mother-in-law from hell. And, when Arsenault married Dorothy's son, she played a very big role.
"I helped him pick out the diamond," said Dorothy.
"She bought my diamond," said Arsenault.
And so it came as a giant disappointment for Dorothy when her son and Arsenault broke up after ten years of marriage and two children. Aresnault said she and her ex just grew apart.
"In the beginning, it was very tough for [Dorothy] to handle, because she didn't want to lose me," said Arsenault. "So it was very hard."
"I am not going to say I wasn't angry at her, but not that I wouldn't talk to her again," said Dorothy.
Fast forward to today. Dorothy gets terrible news about her health.
"My kidneys, I was told, were functioning at 2%, so I started my dialysis. Not too happy with my life," said Dorothy.
The only hope was a kidney transplant. The family went on Facebook pleading for a potential kidney donor. And guess who came forward immediately? Dorothy's ex daughter-in-law.
"Every single time you tell somebody 'It's my ex mother-in-law' they are like 'What' and I'm like exactly. Definately a shock," said Arsenault.
That was ex-husband, Scott's reaction too.
"When I had learned it was going to be my ex-wife, I'm like 'Wow.' Just astonishing, I was truly amazed that she was stepping up to the plate. Co-workers and friends of mine were just shocked, just shell shocked," said Scott.
Then came the next shock. Arsenault was a perfect match.
"She called and said, 'Mom, we are a match,' and of course then no one was talking because we were both crying.
Eight weeks ago, the transplant took place. Arsenault gave Dorothy one of her healthy kidney's and saved her ex mother-in-law's life.
"Of all the people in the world that could give you a kidney and be a match, it was your ex daughter-in-law. That's incredible," said Boyd.
"It is incredible. It was a miracle," said Dorothy.
Arsenault was not happy about how she ended things with her ex, but she's thrilled to be able to help now.
"I never wanted to hurt anyone but unfortunately I did," said Arsenault. "This felt good that I could help my family. I am glad that I could show him [Scott] that I'm not an evil ex wife."
"She's given her a new lease on life, she's a true hero. A true hero," said ex-husband Scott.
No mother-in-law from hell in this story. Just two very nice ladies.
"I love you Erica," said Dorothy.