Does he like me or not? Any advice ?

This guy is my ex bf from around 2 years ago and now has a girlfriend. This guy apparently liked me again about 2 months ago but his gf came around 1 month ago. Now in lessons he stares at me. His gf isn't in this cl. But when i p him on the corridor its like hes ignoring me on purpose he almost looks in the opposite direction. I don't know if hes gone off me fully or just tries to show his gf hes over me. Im not sure. Any advice from you guys ? thankyou x!