Need Some Serious Advice…?

I was going out with this girl I met at college we were going out for a little while and everything was fine. Sex was good and we were getting along fine. Then suddenly she broke up with me. She said we can still be friends and that she just didn’t want a relationship at the moment and I got really upset. But then 3 days after we broke up she posted to twitter to her friend ‘Tell my mam I was at yours last night, i was up all night and didn’t go home.’, also a lot of people have been saying something weird has been going on with her and a much much older guy including when we were going out. She’s had a pretty troubled life and I don’t want to ask her in case I piss her off. But on the other hand if something has been going on with this much, much older guy I really want to kick him to put it straight. But then I’m thinking if I do confront him things could get really ugly and I might get arrested or something. Im really stuck in this situation its the only thing running through my head and every time I think of it it hurts. Please someone give me some advice. We really were getting serious even considering the aspect of a family, so you can see why I’m so pulled by it.