She is a survivor, and victim, of abuse. No one chooses to be a prostitute - every person who finds themselves in that situation has a reason why, in the case of your girlfriend it was as a result of abuse.

Abuse changes your mindset. The abuser changes who you are, makes you doubt your own thoughts, drags you down until they have total control.

She did NOT "allow" herself to be put in that position, and she did not choose to respect herself so little - that was the result of the abuse.

Instead, she DID manage to get herself OUT of the situation - that takes a great deal of courage and willpower. And furthermore... she's told you about it. That takes a huuugeeee leap of faith, and trust, because you can be sure she'd be worried about people thinking EXACTLY what you are thinking about her. That she could or should have done more.

It's quite amazing that she chose to tell you at all. Many people don't open up about their abuse, especially not so soon afterwards. She's just went through having her entire concept of reality and love warped, and she's already taking another chance with a new person. That is so strong and brave of her. She's trusting you, knowing full well that you could turn out to be an abuser as well - because she wouldn't have gotten into a relationship with her ex if she thought he was going to be abusive. She's trusting you, knowing full well how many guys can't handle the thought of their ex having sex with someone else. She's trusting you, knowing full well that a large majority of society will blame her for what she's gone through.

Please don't break that trust she's put into you. Please stop judging her, and dwelling on it. Focus on those good qualities, the girl YOU know. And think about just how brave she was to get herself out of a bad situation and how brave she is for taking a risk on you.