I had sex with my best guy friend?

I've been bestfriends with this guy for about a year now. I've always been attracted to him. We've flirted alot over time, but we've always been just friends. Recently, I've been feeling a little more stronger of feelings for him, but still wasn't sure. We text every day and a few nights ago at a party, we had sex. We haven't really talked much about it, and we've went on doings things like normal. We still hangout everyday, and had sex again. Nothing is awkward or anything, but I'm not sure if he was just trying to use me for sex or if he actually has feelings for me? What should i do? Should i ask him or not? And if so, how? I will reward best answer.