Um, so, I hooked up with one of my best guy friends - again. The first time was 2 years ago, and, it was... not great. To make matters worse - he dated my best friend 6 years ago...

Guess you need more of the story... my best friend and I met these guys a 6 years ago. She and the guy saw each other - I wouldn't call it dating, more of a good friends with benefits kind of deal. We all hung out. Anyway, that was 2006... Then a couple years ago, he kissed me one night. Please remember, the friend that "dated" him was/is in a long term realstionship. Anyway, after the kiss, nothing more really happened for a few months. Then two years ago, on a drunken night we got together. It never went anywhere. We remained friends. Always a little bit of awkward sexual tension. But still friends. We were out with a group of friends earlier this year, and out of no where he says to me "can we go on a date" - it was loud, I had had a couple drinks, so I said "pardon me?" and he was like "NEVERMIND!"... so I dropped it. Then we kissed again a couple months later. Then two nights ago, Him, I and two other friends went out to celebrate his birthday... I watched him flirt with girls at the bar, always catching his eye, like he was trying to make me jealous. We left the pub, and went to the club to dance. I came on to the dance floor, and he grabbed me, drug me deep into the crowd and kissed me. The next thing I know, we're outside and heading to his place... We're talking along the way, and he says "you know if we start dating, I have to talk to Jeff, and you have to talk to Sarah"... I'm thinking holy crap - ***... OK... anways, we get back to his place... and things - happen. We get up, he drives me to my car... then texts me "that was good"... now I can't stop thinking about him!!
WHAT DO I DO?? I like him - but I don't want to a) ruin any friendships b) loose him as a friend c) get my heart broken.

The best way to not ruin friendships/lose friends/get your heart broken is to not have drunken sex with a friend.

I would move on from this and chalk it up to experience.

I don't see how d)none of the above is an option in this case.

Here's why, he said you guys would have to talk to your friends if you started dating, but you guys had sex without talking to them first. It's also hard to go from making out and having sex back to just friends, and if you're feeling this way and are worried about a and b chances are good that you will get your heart broken.