in love with a guy with a girlfriend?

alright so if this is long;sorry. please take the time to read, I really need this help.

alright so(I’m changing names) so theres Dan, I’ve known him for two years and had on & off feelings for him for two years. We never actually met, we knew each other through mutual friends. So anyway, He had a girlfriend, and I told him I’d wait for him. & he really liked me. So I waited. Then I got a boyfriend and he broke up with his girlfriend. Then me and my boyfriend broke up and he got a girlfriend. And I was really depressed and stopped tlaking to him. Then I met Pat-we’ve now been dating for 6 months, but I’ve recently been drifting away from him. This saturday I finally met him at bamboozle. Now I’m in love with him again. I don’t know what to do because I’m horribly depressed by the fact that he has a girlfriend(btw he was flirting with me THE WHOLE TIME at bamboozle. touching my back, hugging me(he kissed my head when he left)) So anyway I don’t know what to do because I’m deeply in love with this kid and he has a girlfriend and I have a boyfriend. I’m willing to break up with my boyfriend for him, but he isn’t. FML. I DON’T KNOW WHAT TO DO.