<human>: Condense the text into a few key points

Been dating my GF for just about three months and other than a couple of fights its been great.  Its both of our first real relationships so stupid fights were kinda expected.

Thing is I have massive jealousy and trust issues stemming from how shitty my first GF treated
me back in HS.  Over the summer while me and her were just hanging out she would go out every sat.  There was this guy there I know she interacted with him. I don't know how involved it got but we asked each other if there was anyone else and we both said there wasn't, I have a hard time believing this.  Shortly after we started dating she tells me she can't hangout that sat night because she's going to a concert.  The same guy is also going.  Whatever maybe they didn't hangout idk for sure.

I get on fb chat this tues, she is also online which is weird cause she is hardly ever on. And lo and behold same guy is online. She says shes talking to family. Which is true. She then tells me this weekend she can't hangout on sat cause she has an older friends bday party at this bar in town.  But she offers to hangout after at 10pm or so. Come to find out its the friend of said guy bday on sat. Idk what his plans are but sometimes if the pieces fit.

I have no proof but my gut is telling one thing and its hard to ignore.  Am I going crazy here?
<bot>: GF may/may notve had a thing with a guy before we were official, and trust issues me thinks its still going on.