"im sooooo sorry I had to come up and talk to so and so (a friend she had a falling out with a while ago)"
that wouldnt surprise me if she was shagging a guy in that hour or so she took to text you.
Dump her I say. You dont seem to be in control, shes turned off from you and now shes running riot. And the ex girlfriend if you dont want to go out with her shag her. She was in your girlfriends PJ's!!! I dont see the point hurting her like igetit said, your the man show your above her. Dump her, move on, play gangi games on her and use the ex girlfriend while shes interested, because at the end of the day poon is poon.