Kissed my best friend and enjoyed it....EEEEEEEEEEk!?

I have been friends with this guy since we were in school together and we always go out on the town nal that. He's my best friend and I tell him absolutely everything as in he rings me every night and we talk on the phone for hours. He managed to talk me into going to this charity event and he dropped me home in the early hours of the morning. I have had a thing for him for a while but since we were friends I just let it be i didn't see anything happening. I thoroughly enjoyed my time with him and the whole way in the car it was very flirtatious and there was such sexual tension there!!! As I went to leave we had an amazing kiss that literally sent me back for more. I had fallen in love with this guy only recently and what we shared was just amazing. The next night he called over to my place and just chatted and we kissed again only to be interrupted by my sister so he left then. I really don't know where this is going should I go for it or would we be better friends. I know he likes me but he's the type of guy I'd like to settle down with in the long run and I'm afraid I'd hurt him. We can't deny that there was something there but I honestly don't want to ruin our friendship. What do I do all help greatly appreciated!