My(40M) gf(37F) of just over a year has hit me in the face 6 times now. What should I do?

Tldr: my girlfriend keeps hitting me in the face and I don't know what to do.

I love this woman but I don't know if I can stay in this relationship anymore. I've never hit her, before or after being slapped by her. She has promised that she wouldn't do it again in the past but it continues to happen. She doesn't just lightly slap me either, she puts everything into it. I've even called the cops on her in the past because I wanted her to to know she couldn't keep doing this but that hasn't stopped her either. The last time it happened she did it in front of my best friends…twice. Honestly, I so badly wanted to hit her back this last time, of course I didn't, but that's not where I want to be mentally or emotionally so I'm now questioning my relationship with her not just for me, but for her as well. Everything else is great except for this one thing when she gets mad. Is this abuse? Will it end? What should I do? Thank you.