How can i tell him its happening again?

report your dad to the authorities if you can. there is no reason to get hit by your dad like that; you are not a complete failure because all the horrible things that happened to you are probably his fault anyways. also, i'm sorry to say this but, i know you still love your dad, but chances are that he doesn't love you back because no parent would hit their child like that and favor the other siblings. as for your boyfriend, you guys are a couple and you shouldn't be afraid to tell each other anything, however since he has his exams to deal with, i strongly suggest to wait until the exams are over and then tell him. he will be there for you no matter what happens so don't worry i'm sure he loves you a lot and will understand you! life is hard sometimes but your just have to keep fighting for it!! good luck and i hope the best of things for you and your boyfriend!!