Tough situation

Linda

So I’m going to be a senior in High school and recently I’ve hooked up with this boy and I’m starting to catch feelings. He likes me a lot and wants to date but I’m hesitant because one of my friends likes him a lot and would probably murder me if she found out about him and I. I don’t know whether to tell her upfront or just wait to see if him and I end up getting really serious. What should I do?