Should I be mad with my best friend and girlfriend?

Should I be mad at this???:

My girlfriend and I were at a bar this past weekend with 5 other friends, one of which is my best friend in town from Ohio. When we were about to leave my girlfriend and my best friend needed to close out their tabs and...

went down to the bar together to close them out. They were down there for a good 5 to 10 minutes before the rest of my friends and I went down there to wait for them to close out their tabs. When we got down there we waited off by the door waiting for them to get done at the bar (they didn't know we were there, but did know we were ready to leave) and when we got there we saw them talking really close (like you would if you were heavily flirting with someone - not just saying this because I have a bias to my case) - they kept putting their arms around each other and they kept giving each other hugs and talking right next to each other's ear (not very loud at the bar though). I didn't think too much of it because I don't want to be one of "those jealous boyfriends" until another 5 minutes passed and 2 of my other friends were like "hey man, it looks like they're about to make out" - and it really did look that way. I got mad and told my girlfriend and my friend we needed to leave kind of angrily and I stormed out (my buzz had gone away because I was driving). My best friend came out and asked me the problem, so I told him and he told me that they were talking about me the whole time - about how my girlfriend needed to quit smoking and stuff. I told him that he needed to respect me more than to talk to my girlfriend like he was (I told him I would never do that to any girl he was dating) - I don't really trust him because he has made out with my sister right in front of me and one time he blatantly groped my ex-girlfriend's breasts. I've been screwed over a lot by people close to me and I'm sensitive when it comes to stuff like this (my cousin slept with ex-girlfriend, my other best friend made out with my other ex-girlfriend all night one night and also tried to putting his hand down her pants, and another best friend took yet another ex-girlfriend on a date to a John Mayer concert and never told me about it). My girlfriend told me that he cares for me a lot and they were really talking about me the whole time. I got mad at her when we got back to my apartment and got in kind of a big fight, but made up a few minutes later.

That's fine with me if they're talking about me and her, but to talk like they were, I wish they would respect me more. She even knew I didn't trust that guy all the way. She's cheated on her past 2 boyfriends (one of which was with his bestfriend). How should I have reacted - did I overexaggerrate or was I justified in my actions, or should I have done more?

I know everyone responding this is going to say: "Man, you need to find yourself some better friends." and I know this...

Dear bch01,
My first question isn't about what happened at the bar but why are you always around your exgirlfriends and why are you still associating with friends who have already did a bad turn? So the thing that all of this has in common is "YOU" so I suggest you sit down and figure out why these things are all around you? Perhaps you are choose the wrong kinds of people to be with or perhaps you feel you don't deserve to have better friends. Either way, I think it's not the situations you need to examine but yourself. Do you love the drama?
Sue...good luck

I THINK SUE IS RIGHT I HAD A SIMILAR PROBLEM ONLY I WALKED IN ON MY GIRLFRIEND HAVING SEX WITH MY BEST FRIEND AND SUE HAD GIVIN ME ADVICE ON HOW 2 GET OVER AND IT WORKED SO I THINK you SHOULD LISTEN TO HER