My boyfriend kisses very scary....?

hes nice and all, from the heart, looks, and evrything, but he kisses very scary. he bit my lip really bad once, and felt bad, but still. and then he slobbers . his ex told me she broke up with him for that. but i feel kinda bad......how do i tell him ...and wat should i tell him??? thanks! and i dont wanna break up w/t him since hes the best bf ever! except for the kissing part. btw hes 14