Usher's ex-wife claims her decision to have plastic surgery was "the straw" which broke their marriage.

The R&B singer married Tameka Foster in August 2007 but filed for divorce in June 2009, just months after she suffered a cardiac arrest while in Brazil to have a cosmetic procedure. She has confirmed it was her decision to have the operation - which was never actually performed - which caused the failure of their relationship.

"Pressures from the public, you know," she told ET when asked about their breakup. "But then I did dumb stuff. I went to Brazil and tried to get lipo and almost died, I think that embarrassed him too. Like, 'Oh no, I'm packing up, she's a nut.' I think that might have been kind of the straw."

Tamara, 43, admits she wasn't ready for how much her life would change when she tied the knot with the 35-year-old singer. He tried to support her, but in the end she took things out on him because she found being in the limelight so hard.

"I made a lot of mistakes. I undertook a lot in getting into such a public relationship... He always told me, 'You gotta drink a lot of milk.' You know, you gotta toughen up because I wasn't ready for the scrutiny," she explained. "And then to just hear the things people would say about me, it hurt me a lot. And I think I nagged him as a result of what I was going through. I was just always in his ear. I was being such a b***h."

Tamara and Usher have two sons together and she also has children from previous relationships. When the former couple's marriage broke down they engaged in a lengthy, and public, custody battle, which Usher ended up winning. She still can't get her head around what happened and hinted Usher's star status had some impact on proceedings.

"Millionaire more importantly," she replied when asked what it was like to battle a famous celebrity for custody. "That played more of a role in the outcome, a very rich person. I've been a mom for 23 years. I have a grown child. I've been a mother since my ex-husband was a little boy. If you think about it in that way."