@FogCatcher if you have left (which sounds like it was the right thing to do) you need to immediately let go of the expectation of an apology or him asking for forgiveness.
Just focus on moving forward with your new life.
There is NOTHING available in terms of remorse where you are looking for it. He does not have that capacity or inclination. His inability to self reflect and to deflect to you is his character defect, on top of the way he treated you. You can't change it. Just let it go and move on with your life.
The expectation of a "sorry I did that" will keep you trapped forever. You are in a way only harming yourself by keeping this channel open. Just accept that he is not a good person and he is not the person for you and you have moved on for yourself and your DC - nothing more, nothing less.
Seek counselling if you need to but just stop expecting someone who has repeatedly showed you that he is not capable of being kind, caring or respectful to change. If he does decide to work on himself, that won't be because of back and forth texts between you.
Block the text messages or mute them if you need them for reference / about DC.
Minimise contact - make it about DC only. Get a parenting app if you need to.
Stop entering into conversations about the relationship and who did what and what went wrong - it's FINISHED now (hopefully) - there is nothing more to talk about as you have left.
Also, please stop posting weird reversed posts to try to validate your decisions.
Spend some time reminding yourself of why you left and why that was the right decision for you and your family, and then focus on your new life, not the old.
Leaving is not easy. I salute you for that. But you need to stop looking to the past and really focus on the future and what kind of life you want to give your DC going forward and what kind of life you want for yourself.
When you leave there is a lot to focus on - admin, DC welfare, your own welfare, detangling, unpicking previous arrangements, creating new structures, routines, rebuilding finances etc. Focus on things that will take you forward not back. I say this only because I too left. I don't read or respond to any messages that are not about the children. It took about 6-8 months for him to get the message but it's so peaceful now. My phone is calm. I can open my messages with zero anxiety. There are no more long, still abusive, conversations. He got the message eventually that I am gone and that there is nothing to talk about anymore other than the kids.
I do not engage with ANYTHING else and he knows this now. I think you need to stop engaging with him - by phone / text and also in your brain.
I am not trying to be harsh but you need to work hard at building your new life and it is really hard work. Do it for yourself and do it for your DC. Free yourself.
Disclaimer: did not read every single reply on the thread.