Violence

I've been with my boyfriend for 3 years, we live together, and we have our good times you know, but sometimes we fight, and he Hits me... Really hard, he turns into another person I swear, and I've thought of leaving him, but I love him so much, like I said we have good moments, VERY Good ones, and that's what I love about being with him, but I Also know I deserve better, I want him to change but I really don't think that will happen, and it kills me to live like this, u know I just want to wake up one day, and don't feel love for him, but I can't! I've seen people here that have gone through the same thing, I really want to know how you guys ended those relationships! I really need some advice..