Singer Kelis has accused her ex-husband Nas of mentally and physically abusing her during their marriage.

The former couple wed in 2005 and divorced in 2010, and now the Milkshake singer has revealed she made the decision to leave him while she was pregnant with their now-eight-year-old son, Knight, because she didn't want to bring her child into the alleged abusive environment.

"There was a lot of mental and physical abuse", she tells

"An intense low... we had a lot," she later adds. "It was really dark. A lot of drinking. A lot of mental and physical abuse and it got to the point where if I wasn't pregnant, I might have stayed with him. I was pregnant and it was a mess and I felt like I wasn't going to bring a child into this."

Kelis also claims frequent alcohol and drug use led to turbulence during the relationship and they never had a "normal" time together.

"We had really intense highs and really intense lows. It was never normal," she says. "An intense high would be when money was rolling in. But I was 22 when I met him. We were drinking a lot, getting high a lot. So when that comes down, it was bad."

The 38-year-old admits they both physically assaulted each other, but she made the decision to leave the rapper after she saw the pictures of Rihanna following her domestic violence assault at the hands of her then-boyfriend Chris Brown in 2009.

"When the Rihanna and Chris Brown pictures came out I thought about coming out, because I also had bruises all over my body," she continues. "But I didn't say anything because I'm private. But seeing her the way she looked and then looking at myself... I felt embarrassed."

Kelis and Nas are currently locked in a custody battle over Knight and in the interview she hits out at her ex for allegedly not being consistent about spending time with their son.

"A parent isn't about showing up when you feel like it," she adds. "You can't not show up for months and then show up and try to make up your own (visitation) schedule."