Should I confront cheater or just leave it alone?

I don't think you need to tell her that you hate her guts (unless you're absolutely, completely 100% sure that you will NEVER return to her), but you can certainly say, "Look, I know you cheated on me and that's why I broke up with you. I thought you were a better person than that, but obviously you're not. So stop texting me. I'm not interested in you anymore."