How to deal with hooking up with a coworker?

Hi!
Found myself in an odd predicament.. I have a good friend of mine (who is a coworker). I've known him a few years, he's always had a girlfriend. She's never treated him great, they break up and get back together all the time. The only reason they are still together is because she is dealing with some tough life events and he feels bad leaving her. Anyways, we had a work event this weekend and drank a little bit, and he ended up kissing me and we made out for a little bit. He told me he had always had a crush on me. We haven't really spoken since. I might be interested in pursuing things... i just don't know what he wants from me and I'm not really sure how to act or what to say the next time we see each other. I don't want it to be awkward, I'm not sure how to clear the air. Any ideas?
How to deal with hooking up with a coworker?
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