What really happened to Ushers wife?

Supposedly she had a heart attack on the operation table due to the fact of her having plastic surgery. I think that it was her way of getting out of a relationship with Usher. The money was nice but at the same time you can only handle someone for so long.

Since Usher has been married he has only been making married mans music which isn't as sexy and isn't as stereotypical hip hop. Ushers wife is guaranteed money regardless. But the fake heart attack was performed to think shes dead and can get out of the marriage