to be honest i dont know if i am the very best person to ask about this, because i feel like my views on such things are different than lots of other people.
i inappropriately drunk text people too often. i talk to my ex steph almost every day. i am good friends with and frequently hang out with people i have slept with and/or dated in the past. ive at least made out with the majority of my good friends (lol) and ive had sex with a best friend or two in the past also. i still hang out with them, we get drunk together, i dont have an issue with it, and i dislike the idea of my significant other not trusting me, and therefore having an issue with it. if i was dating a girl who wanted me to stop hanging out with such people, i would not put up with that.
maybe thats just me though.

i suggest that instead of just being pissed off and upset you TALK to your girlfriend. clearly you are insecure about something (in yourself, or in your relationship), and/or you have trust issues. i dont mean to lay down accusations, but if you were feeling secure in your relationship maybe you wouldnt be upset by your girlfriend "hanging out" with someone she made out with once.

this is just my opinion though, and maybe you feel differently. try to be honest with your girlfriend about why you are upset and what you are so afraid of. be prepared though that she may not like you telling her who she can and can not talk to or hang out with. (because thats how i am)