@PithyBeaker People with PTSD are especially susceptible to trauma bonding or manipulation.
Without going no contact you will never recover and could easily get pulled back in.
Do not doubt yourself, he's trying to grind you down
On some level I suspect you may even be questioning if you did the right thing, because after all, he is trying so hard, promising so much, which, in your mind, could mean, he really must love me and you are so deeply invested still.
It is not love, it's pure manipulation.
Part of the difficulty may be, is you still love him, you were prepared to continue the relationship but without him and his kids treating you, your son and your home with zero respect.
He is still not respecting your boundaries, he is harassing you, trying to overwhelm and break you down to accede to his wishes
For you to heal and move forward, no contact is the only way you will recover, which is easy for others to say when you're feeling lonely, vulnerable and unsure, probably even more so when your son is away at his Dad's and you're left replaying everything over and over.
You are so very brave to have come this far, you are, after all, only ~six weeks on from setting your boundaries but remind yourself of your first post on your original thread.
Trust yourself, not him.
Good luck @PithyBeaker we are all rooting for you 🌻