Fluther, please help. Is what I'm feeling right now for good reason? Please read details?

Yeah so this will probably be a little harsh sounding but lets get started.

I dated Bill for 2 years. We broke up 1.5 years ago. We’ve remained friends and continue to hang out, especially the past month or so, and well ok basically we’re dating but he doesn’t want a girlfriend so we don’t call it that. We just do what we do but it’s not official or whatever. Who cares right.

So Bill has a female friend named Sue who he hangs out with a couple times a week. They are good friends but when I asked him last time about if he liked her after he was flirting with her all night, he said no and that he tries to be creepy around her because she doesn’t have any interest in dating, sex, whatever. And I do know her, and she is like that a little bit, so I took his word for it.

Tonight his brother had a party, we were all there. I wasn’t drunk. He was a little, she was very. Every time I looked, they were hugging or rolling down the hill together. He didn’t really talk to any of the other people there but he swears he talked to everyone. So later we were all sleeping in his bed, six of us, I was on one side of him and she was on the other and we were all pretty close and next thing I know I feel upward and they are making out! An inch from my face! So I stated loudly “Are you guys making out?!” Neither of them said anything. I got up and drove home.

What the f? Is that strange? Would you be jealous in a situation like such? I know it’s easy to say that we’re not dating so I can’t be jealous, but he was right beside me, making out with another girl he constantly swears not to like. wtf fluther. what. the. fuck. Of course I’m probably overreacting since this just happened, but give me your input anyhow, and please try not to be rude, I’m a bit sad tonight.