I never thought I would do this!

[neonsparkles]

OK, I thought I would never ask a question on this forum, but here I am! I guess I just needed to advice of people who don't know me or this person in real life so it is unbiased.

Here is my problem: I like a guy who has a girlfriend. First of all, I would never do anything while he was with someone else because I have been cheated on.... so that is not an option. There is more to this though.
This guy has flirted and shown major signs of interest since last year, but I was going through the break up from hell (it lasted 5 months.....yeah) and I just recently began dating other people. It took me this long to realize that I have liked him since last year too.... and now that I finally realize it, its too late. We would have been together last year had I been ready.
He and his current gf haven't been together that long ( a month or two), and have already done the "break up and get back together" thing. He and I are pretty good friends, but lately he seems more interested in hanging out. I have seen him out at parties twice without his girlfriend and he always buys me drinks and talks to me. I have to stress he is usually just hanging out with his guy friends and isnt the type to flirt with other girls, so its not like he buys other girls drinks or flirts with them also. (And trust me, its not wishful thinking on my part, I have seen him and he just isnt a natually flirty guy). He called me tonight as asked if he could go out with me tonight to the bars... which his gf isn't old enough to even get into. AND... he is going away for the weekend and instead of spending time with her he wants to hang out with me.
Basically I could go on.. but I will sum it up and say he acts the same to me as he did before he had a girlfriend, he always gives me back rubs, flirts, gets all the things i need for work and class without me even asking him to do that... and I don;t know.
I am still dating other guys of course... but none of them have the same appeal as he does.. and I am nervous about going out with him tonight (going to the bars and all of that you know are never a good idea when you are trying to hide a secret!)
What should I do (and I dont want to cheat.. so thats not an option?) and have any of you been in this situation?