I've been crushing on a friend who has admitted to liking me, but I'm not sure what to do... any help?

I've been friends with this girl for over 3 years now, and have crushed on her a few times. Over the last couple of months, however, I developed another one on her. I told her about this one, and she told me that she felt the same way. We decided to take it slow, considering we were both hesitant about how us dating would affect our friendship. One night, I kissed her out of the blue, and she seemed to like it. We continued this way for around 2 weeks.... even kissing at school once... but after the second week, she told me that, and i quote, "her heart wasn't in it." I'll admit, I was angry, but I moved on, continuing to like her, knowing that I'd be in mental agony whenever I was with her. However, around 2 weeks ago, she told me that she still likes me. I don't know whether I should or should not pursue her again romantically, and it's been eating away at my mind like nothing ever has before. I feel lost as to what I should do, because I don't know if she would want to pursue a relationship even though I do, and whenever I try to bring it up, she evades it.... quite cleverly, I might add... What should i do?