Someone deleted my account

My ex girlfriend and I had been using the same account. She moved out, got her own Xbox, and for a while everything was ok. Two days ago she decided to delete my name on the account so now all of my purchases and everything are gone. She thinks it all belonged to her when my debit card info and everything in my name on my username are right there. How do I get my account back?? I'm pissed

:)