<human>: So I got out of a LTR about 4 months ago and this girl (now my gf) tried dating me when I was in my LTR. I told her I had a gf and couldn't date her. So when i ended my LTR I started talking to her and dating her. About a month or 2 before we actually made it official she had had sex with another guy. (While we were having sex as well) but we weren't technically together. 

Should I be mad that she slept with another guy while we were having sex and planning on making it official soon?

Also she did tell me she was sorry and she never would cheat if we would of been actually together.

Can you give me a shortened version of the text?
<bot>: my girlfriend now, had sex with another guy about a month before we officially became committed to each other. Should it bother me or make me angry?