My best friends boyfriend?

So 2 months ago one of my best friends started dating this guy. I never really thought about him before because I had never had any cles with him and we hang out with different people so I really didn't pay any attention to him. After she started dating him at the beginning of this year and he was igned to my homeroom cl, I started to kinda like him but I hid it by pretending I hated him. I'm still pretending and we fight all the time but it's kinda like play fighting but kinda not. I don't know what to do because nobody knows I like him and I don't want to tell my friend. What do I do?