I don't know what to do

This guy that I have been in a flirtatiouship with have been kinda getting closer some days we talk some days we don't but when we do I honestly feel like I'm falling for him. I really like him and he's first guy in a long time to make me feel anything close to butter flies. But he's my ex boyfriends best friend. We've been keeping things on the DL for awhile even trying to carry on things with other people to keep people from knowjng, were in high school and both in positions of social power and could potentially end up in deep shit because of everything. I want an honest to god relationship with him but I have no idea if he'd be interested in it I've told him to chase me and win me but I don't know if he quite gets it I just don't know what to do I'm falling for him and shit im screwed help!!