ok, good stuff! well the good news if you really had sex w/ her like 7 out of 10 days, if you were even halfway competent then she's going to have a LOT of feelings for you and you probably have a lot more hand here than you realize. you have a couple plays here, but like everybody else here said... you better figure out what it is you want from her first.
most likely, when she went over to your friend's house, she was trying to make you jealous. that's a textbook play, and you really have to be a cold-blooded pimp to not feel jealous. of
course you were pissed, it's natural and you shouldn't feel sorry for it. i've had girls i cared
nothing about pull this on me and i was fuming, thinking i made a mistake. so she was checking to see if you had any feelings at all for her, and you confirmed it.
you can 1) bring up the incident again and ask her if she was trying to make you jealous (most likely she was, but she very well may not admit to it), tell her it made you feel weird and it was then that maybe you realized that you wanted to date instead of being friends. this is the most honest approach, but probably the least effective.
-or- 2) run the same play back on her. tell her you met this girl who's like a french model or something... make her sound virtually perfect but then say you're not sure whether to take it further because of x. x being a minor flaw that a true friend would tell you to get over. if she tells you to go for it, you've got problems. if she acts jealous or blows the flaw way out of proportion and tells you not to date the girl, you're golden! just lead her on for a little while thinking you've found someone better than her and NOW you're considering starting a relationship. that will probably make her feel exactly how she made you feel. from there, once she's solidly on the hook, you can say something about having more feelings for her and how you think you'd rather date her instead.
3) if you really don't want to date her, then you better get the f out of LJBF territory with a quickness. your best friend here is alcohol. get her drunk, often, and flirt / kino escalate, often. let her know, first nonverbally, and then verbally if you have to, that you have no interest in just being friends. have a strong frame and be unashamed about what you want.
good luck, buddy! i've been there
