Slept with my Best mate..Now what?

We have been close for 3 years and both of us have had our fair share of relationships.. and we have both always thought 'what if' .. curiousity got the better of us the other night, and we planned to have .. planned as in we talked about it a fair bit over the last week. & it was great and felt right. We both clearly enjoyed it. Ok problems are now.. a) he has a gf b) im single .. c) my feelings have gotten more intense towards him. He wants to do it again, but I dont want to ruin the friendship but i dont want him to not notice me as more.. How should I play out the next few days? I dont want to come across desperate. Give me any opinion people!