IDK Liz, from all that you've shared I see him progressively letting you in closer - sharing a home & being so involved with his kids was a big step of trust & respect, IMO. (aside from all the other great "actions" he displays)
I'm wondering if it's no small coincidence that you are feeling that you are "setting yourself up for future heartbreak" following a trip back to court to battle with your Ex? PTSD being what it is, it bleeds over from the trigger into the rest of your life, right?