Can't decide what to do with my best friend.

So I've known, let's call him John, for about 9 years now. We weren't always close but we've had a pretty solid friendship the last 5 years. Recently I went to visit him and his family on holiday for a few days. On the last night I was with them, we got raging drunk and had sex. The following months we acted like normal but there was definitely some sort tension. Last week we got together for a movie night and I ended up staying the night... We did drink again but we definitely weren't as drunk as the first time and he was much more affectionate. Now we're back to where we started the first time around but I don't know if I can continue to sleep with him and let it not affect our friendship. Should I end the sexual relationship to save the friendship? Or should I put myself out there and risk losing him all together?