Don't spend time at home.
She is the biggest bitch in the world for doing that. She could at least have the decency to fvcking keep it away from you.
What a fvcking bitch!!!!
Man, get angry, go fvcking scream your face off at her, kick her out regardless of what your wussy roomate thinks/doesn't think ... you are in the right here, not her.
Just pick up all her sh!t and dump it on the lawn, don't let her back in. Change the locks do what you need to.
Anything short of actually hitting her.
edit:
If you're not pissed off enough to do that, then that means that you're down and out and maybe you're missing her, wanting her back or whatever.
First thing is first.
Recognize that it's OVER .. whether you like it or not. Now, once you've got yourself together go take care of business and kick that bitch out of your place and out of your life. She ain't worth it man. Don't play mind games with yourself, don't keep telling yourself that you love her .. don't be upset .. you have nothing to lose at this point but your dignity, and you want to keep that by all means.
I've been there man, just get tough and tell her where to go.