So last night this girl I've been seeing about 3 months very regularly, everything seems to be going well, says she's going to dinner w one of her guy friends. He wants to take her out before she leaves to go back to Greece which is where she's from (she's going for a few weeks just to reapply for a new visa and then is coming back, she also invited me to stay w her in Greece for the new few months and still wants me to as of this moment)
She leaves at about 7 and comes back at almost midnight. I didn't think anything of it because she always is late. She brings me back food from the restaurant they ate at like she said she would. The last 24 hours have been typical we have a lot of fun nothing seems weird.
Then a couple hours ago she's going through her facebook in front of me and on the messages I see one that's from some guy that says "Thanks again for last night. You were great."
It struck me as weird for a second, then it set in about an hour later and I realized wow she probably had sex w this guy. I don't want to ask her about it but we've had some nonverbal exchanges which I know can be misread but I have a feeling she did it. Now we are not officially bf/gf and haven't talked about being a relationship but she stays over days at a time and is always treating me like a bf. She's always kissing me and holding when we walk anywhere.
So I'm wondering what should I do? I'm like 90% sure she had sex w another guy but I have no proof except for a message I saw before she quickly closed it. I don't want to date a slutty girl who's going to be off farking other guys while I'm not hooking up w other girls, and I also don't want to hook up w other girls just to get back at her because honestly that will just lead to bad karma for me which I don't want.
I basically just froze her out the last few hrs since I realized this...now she's asleep in the other room and I'm wondering what I should do?