Becky talks to Oprah what it was like to discover that her birth mother is a cold-blooded killer.

Mother to most of us is the one who provides us with a shelter of love and affection. We know that she will be there to protect us whenever needed. But what happens when you find out that your mother is the killer of her own child.

On tomorrow’s episode of Oprah Winfrey Show on BIG CBS LOVE, 27 years old Becky talks to Oprah about her mother Diane Downs who brutally shot her children. The incident killed her 7-year-old daughter Cheryl, paralysed 3-year-old Danny and 8-year-old Christie had lost so much blood she suffered a stroke.

In 1983, Diane told the police that she driving one down a rural road in Oregon when her three children, who were asleep in the car, were shot at point-blank range by a stranger in the dark. But when the truth prevailed, it shook the world. At the trial, Diane's surviving daughter, Christie, took the witness stand and testified that her mother was the shooter.

Diane was convicted of shooting her children and was sentenced to life in prison plus 50 years. During the trial, it was revealed that Diane was pregnant. Ten days after she was found guilty, Diane gave birth to a baby girl who was adopted soon after.  Today, that baby is called Becky. After years of hiding the truth, Becky decided to speak up about what it was like to discover that her birth mother is a cold-blooded killer.

Becky says she always knew she was adopted, but when she turned 8, she started asking questions about her biological mother. When she was 11, Becky tricked her babysitter to tell her the name of her biological mother. When she found out about Diane Downs, she went to a book store nearby and went through Small Sacrifices, a book on her mother. When the truth about Diane started sinking in, Becky began to believe that Diane was not a mother, she's a monster. From there, Becky says she went into a downward spiral. "I started drinking, doing drugs, sleeping around," she says. "I really was just trying to find love from anywhere I could. I ended up getting pregnant when I was 17 years old."

At 20 years old, Becky found herself broke, homeless and pregnant for a second time. "I made the hardest decision I've ever had to make," she says. "I decided to put [my son] up for adoption. I was in so much pain from losing my son that I wanted to relate to somebody, I wanted to know that the pain I felt was okay, and I reached out to Diane," Becky tells Oprah.

Becky wrote a letter to Diane in prison telling her who she was. Diane reacted normally on Becky’s first letter. But as time went by, Becky says her letters got frightening. Becky says she now regrets ever writing to Diane. "I have an amazing family, and there's not room in my life for someone like Diane Downs," Becky says.

Diane may be the woman who gave birth to her, but Becky says they don't have to have a connection. "I was raised in a godly home, and I'm well adjusted," she says. "My son is amazing and well adjusted. And if I don't want to, I don't have to think about Diane again."

Watch Becky as she talks to Oprah about her killer mother and how she dealt with her life after she found out the truth on BIG CBS LOVE on Wednesday, 8pm.