Sounds like you've already cut your losses. It's better to get out now before she really turns psycho on you. Her own house, huh? She might very well be "doing things" on her own.
Don't be
over this. Consider this a lesson well learned and move on. Just don't let the old gf find out about the new gf until a few months go by. I don't want to read about you all on the news!