I like my best friends boyfriend.?

I've liked this guy (lets call him collin) since about the eighth grade. Since then hes been dating my now best friend "sue". Im now a sophomore. Lately hes been EXTREMELY flirty including hugging me unnecessarily tightly including putting his hand over my chest area, putting his arm around me, and doing cute little things in thr hallway at school like blowing my hair. Last year we sort of had a thing, he and my friend even broke up over me. I thoughtvi was over him but its even more clear to me that i feel like hes who im supposed to be with. Were also going to the same college. What should i do? Ignore it and move on or flirt back and try to win him over to me?