Update: They left. They left and said they cannot ever come back, even if they heal their trauma, even if I heal my trauma, because the relationship itself is too damaged. They also said they're just starting to realize their trauma was way worse than they had realized, and contributed much more to the bad dynamics than they'd thought -- earlier they thought it was mostly mine that was the problem, and as we were discussing the breakup they realized just how much harm their trauma had done to me and even brought my own out too (which hurt them in turn).

We were just doomed. We were just fucked from before the start. We were completely and utterly set up to fail. I'm glad you and your partner were able to reconnect, but my partner is too principled and stubborn to be willing to do that with me -- when they say it's over and they'll never be back, they mean it in a way that I cannot doubt. Honestly, your case is probably a great outlier, most people never reconnect after splitting up.

I don't know what to do with my life now. I restructured so much of my life to be devoted to them. I got through the brutal work days because I wanted to provide for them. I worked on myself to be better because I wanted to grow and heal for them.