I think one good remedy that will help you to start feeling more confident in yourself, happy about your life, and not used is this: Put her things outside your apartment and change the locks. She can mooch off of one of her other suckers - er, I mean... lovers.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein