Don't worry, she did you a favor. You should thank her for letting her know she is a slore and move on. The "friends" that you've lost weren't friends anyway, so you are better off without them.
Be relieved that this didn't happen further down the road when you were married and had to divorce her.
You didn't do anything wrong. She is the problem, so don't doubt yourself one bit. Sounds like she was not worth it anyway.
You'll know when you find the right girl. Until then, don't take the BS from anyone.