@DietCokeAddict19 I am not a fan of armchair diagnoses but I will say that there are aspects of covert narcissism in his behaviour. Doesn't mean he is one, but you can still take some learnings.
The key thing I'm noticing in your texts is that he's very self absorbed, lacking in empathy and very much the victim. Men like this love women like you because you tend to feel an over inflated sense of responsibility and overcompensate for perceived selfishness or other failings, often as a result of the sort of upbringing and scapegoating you've described in your past.
I totally get why you don't want to block him and at this point, I tend to agree. If there weren't the DC to think about, sure, no problem. But there are.
But the single biggest thing to remember with people with narcissist traits is that they need "supply". What that means is they need your attention. Preferably positive attention - "you are so great" is, of course, the preferred option. But "I'm so sorry, you've been so wronged and here's how I can help you" is good too. At a push, they will absolutely take, "You are a dickhead and I hate you" because.... it still allows them, in their OWN narrative, to be the hero AND victim at once ("I did so much for her and look what a bitch she is to me").
So don't engage with the texts at all. Ignore them. Or, as I think has been suggested previously, send a single emoji. Thumbs up is often a good one.
I don't know what was in your last text and I'd be inclined to say it doesn't matter, but I suspect you will feel you can't just stop engaging with him completely with no warning, so if you absolutely must, first send a single message saying "I can't talk to you anymore. this relationship is over and we both need to get on with our lives. I wish you all the best." Then ignore or emoji only.
As for the DC, I think you just have to keep talking to them. There's a fairly good chance he will turn on them at some point so look out for that. On the plus side, once he does, it will be a lot easier to encourage them to cut contact completely.
It's hard. I know. But you can do this.