Does my bestfriend (who i'm in love with) act like this on purpose? read on, i NEEEED advice pleaseee?

Okay i'm bi and my best friend knows i'm in love with her, anyways she's straight, she was cool with it, but she said stuff too me like at school she has to stop herself kissing me, and she wants to kiss me and **** like that. Anyway we agreed we will, but i was trying to make sure she was fine with it as she's straight and all ( Well she told me she wasn't sure but it;s so obvious she is ) So for weeks this went on the whole "talking" about it then one friday i stopped at hers,we was supposed to that night, but it just didn't feel right i left it, although the night before she said she wouldn't be able to help herself anyway we were just messing about ( as friends not that type of messing about ) and i was lay on top of her on the floor (she was on her stomache) anyway she was on her laptop and she asked for a mage so i gave her one, and jesus she sounded like she was ing lol ( but she wasn't ) Nothing happened, just a normal friend sleepover, i was cool with it was a good night but like after that at school she'd been quite distant with me, it pissed me off a bit the way she was acting so i just backed off, then that night she said she doesn't wanna do the whole kissing thing anymore, just leave it and stuff, anyway we had a tiny arguement ( not over that just over her acting a **** at school ) and i just walked out and apprently she kept asking for me and stuff, i mean one minute she has to stop herself from kissing me, the next she doesn't want to anymore and is staying away from me then she doesn't stopped asking for me? What does this mean please no snide comments because i know this question will sound like a little kid the way i've put it, but some advice would be nice please :)