How can i repair a relationship i destroyed or is it to late?

We have been dating for 2 years. 4 months into the relationship we were both not ready for a relationship. The result was a lot of fighting, a lot of break up attempts and a lot of feelings hurt.

I cheated on her and used it as an quick/easy way to end the relationship. Her true feelings surfaced and she came back to me while my true feelings hid deeper and deeper and became a terrible person.

Present day (a year and a half after the cheating incident). I find myself more in love w/ this girl than I have ever felt in my entire life. She, some how, at the same exact time decides to stop caring that much for me. It is heart breaking and she is getting more and more distant.

I’ve realized the error of my ways over the past 2 years, i need to make it up to her. To save her, to save myself. I really loved each and every single moment of the past 2 years. I had no idea she was constantly questioning why she was still in this unofficial relationship and it appears now she ran out of answers.

She says she needs time, she is talking to other guys online, she has spoken about the freedoms of a single life, she has keeps bringing up how i cheated on her so long ago.

I don’t know what the best course of action is. every time i try to end it again for her benefit she pulls me in and says she still loves me.
She will not commit, she will not talk to me seriously about the relationship and she will not let me break up. It feels like she is slowly coming back to how things used to be (extremely slowly)

A lot of very emotionally driven conversations in the past 2 months that has only left us both hurt, this can’t go on. It is to unhealthy for us both.

What is the right thing to do?