Is there a safe way to ask my g/f if she is cheating on me with her ex?

[Ed]

I have been with my g/f for a few months now and we already live together. She has an ex who for lack of a better word is a total dick. They dated off and on for 3 years and it was not the best of relationships according to her. They have hung out at random events with other people like co-workers and at darts on occasion. He has several times gotten drunk and pissed her off to the point of them not talking for a few weeks. Recently i heard they ran into each other at a birthday party and he was drunk and started ragging on her and I, lots of negative comments about me. He has never ever said anything to my face and the few times we talked we got along well. I just recently heard when she went out a the other night with some of our old co-workers and friends that they all got really drunk. She never mentioned her ex being there even when i in a round about way asked who was all there. One of my friends has a shared friend with my g/f and claims that my g/f was texting this girl that night. My friend said she only saw a bit of the conversation but did for sure see that my g/f was hanging out with her ex at the bar among our other friends and former co-workers. The girl that was texting with my g/f then went on to tell my friend that i had given my g/f a "free pass for the weekend and she was going to get her ex drunk and try to sleep with him." I of course am stunned by this. It sounds a lot like gossip to me but i just recently noticed that my g/f and her ex are FB friends again after her removing him because he was being a dick to her after we started dating. I only know that he recently started "being nice to her" in her own words since we moved in together. I don't know if i should just ask her in a calm manor and wait for her response before telling her about my "sort of proof." To top off the night in question my g/f also drunk called me and asked me if i loved her and that we should have sex when she comes back from visiting her friends and family for the weekend. Since we have not progressed to saying "i love you" out loud yet i took the chance to tell her i did. She replied later via text "Love you." So the timeline i gathered was the supposed conversation i was warned about happened around 10:30pm and she called me at 10:45pm to chat for a min or two about her night out. She then called me again at 1:30am for our last conversation of the night and the text followed about 10 min later. So am i being paranoid or do these sound like valid reasons to ask her?

PS i know its long story, but i feel like i should seek outside help since very few people i talk to have valid advice.

[webcatman]

NO. If she wants to go back to her ex jerk boy friend, you should be glad to be rid of her.

[Jiao Li]

This girl sounds like a idiot
She gets drunk and hangs out with her ex. Why are you with her? Dump her now.

[MikeTbob]

Disregarding all the he said she said stuff. I would just ask her in a nice calm and caring way, face to face. Then it's up to you to decide whether or not you believe her. If you can't trust her then you probably don't need to be with her.
A little harsh but true. Trust is the biggest issue. Without it, you have nothing,