How do I fix a broken relationship?

Help! I’ve cheated. Okay. I feel the eye rolls and scoffs already. That’s okay, I deserve them.

I’ve been with this person for over five years, I cheated in the first year. Ugh, I know. I was forgiven. The three years after that were peachy. Great relationship, hardly any fights, no more cheating. I haven’t cheated since then. However, we broke up last year. Had we been together this year would have been our sixth year. In the year break up, I slept with someone else. (About four months ago, nothing serious, just a hook up) and my ex wanted me back. I was thrilled. The year without her was one of the worst of my life.
She asked if anything happened in the year we were broken up, and I admitted to it, because if anything I wanted her to trust me. She won’t forgive me. At all. And it’s been about four weeks since. I really do love her, and I’m sure she loves me.. so how do we both move on from this?