Moving on is difficult because I loved her passion for us.
I was right out of a divorce so I was not fully able to completely commit to this relationship emotionally. I was very guarded and always looking for an escape plan.
If I were to re-engage and she were to accept a reconciliation the harm would be hurting her again. I have broken it off 3 times. I will not even reach out unless I'm certain I can put in the work. The other times I reached out because she kept engaging and I was experiencing heartbreak.
It's been 4 years so I am a different person and I am 4 years further away from my previous divorce which makes a big difference. My emotional maturity and readiness seems to be improving. I'm a different person than I was 1 year ago.
I'm sort of in that position now. I just divorced after 19 months apart and I met someone online about 8 months ago. We've grown super close and I love her, she's my best friend in the whole world. Yet as the divorce date was approaching, even though I was completely alone, I started feeling guilt for giving up on my wife too soon- I was playing both sides of the fence, so to speak. It was very unfair to the new woman in my life.
What I realized is that I had to grieve my marriage and accept that chapter has ended. For me personally, this was different than grieving my wife...the marriage was our family of four and all those memories together. My ex-wife did terrible things and made terrible decisions, so I accepted that there was no path to reconcile over a year ago. Yet my heart still hurt and I couldn't understand why.
Your situation sounds very similar- you're afraid to repeat the past, so to speak. But you also have to realize that the past is dead and you can't live there anymore, no matter how badly you want to. Your mistakes are written in stone (so to speak) and can't be changed, and the only thing left to do is heal from them and begin to move on.
If you want to re-engage with the new love, just do it honestly- show her your feelings and complicated emotions. Let her have a say in whether or not it's something you guys can work through together. I get the fears of hurting her because I have those identical fears in my new relationship. But I chose to be vulnerable with my emotions and it was the correct choice for me.
If it helps, she's hurting without you as well. There's no sense in punishing yourself for what might happen in the future; just tell her in an open and honest conversation what's really going on.