Nipple biting baby

My 3.5 months old baby have been biting my nipples every time she latches the past week. It hurts so bad that I get goosebumps all over while using all self-restraint to stop myself from slapping her lol. I'll hit her thighs lightly and say no no while I scream out in pain. She seem to find that funny and will do it again. #pleasehelp Mama please teach me how you deal please! I'm very scared to latch these days.