If you’re at peace, that’s all that matters. He must be hurting a lot. You can say, “I’m sorry this is so hard, but I have to do it and I won’t be changing my mind.” You can also say, “I won’t be responding to texts like this anymore,” and then don’t respond. Don’t egg him on by being polite. He will stop eventually.
I feel like you stole my story and wrote it. I am at peace, too. I have decided that l only respond to chats about the kids, anything else l pretend l didn't see.