Oh my, this sure is confusing. I see there is also a lot of confusion and (unjustified?) guilt on your part around your initial separation. Now that you've established the fact that he was not in a PTSD crisis, but chose not to engage you as he'd previously agreed upon, this looks like a different beast entirely.
In that sense, it becomes a larger question as to his actual emotional availability (even beyond PTSD) in the past and now, as well as your compatibility when it comes to relationship values and parameters (and also your motivation, willingness, and reasoning in continuing to make this work.) Him not acknowledging your perspective on the breakup sounds (worst case scenario) like a bit of gaslighting on his part. To infer that you actually respecting his boundaries in breaking up with you was a betrayal, as well as offloading his responsibility onto you, is also somewhat manipulative, and (very effectively, as we can see) spins you into a web of guilt and "what if's" that will make you stick around for another spin cycle, hoping to rectify and rebuild.
Is there a possibility that you two are now rekindling each hoping the other has changed? You thinking maybe this distance has cleared his head and made him more willing to compromise; him thinking the distance has cleared your head and you're now willing to accept what he has to offer without asking for more?
Look at his ACTIONS not his WORDS, as well as their mismatch. Also remember that boundaries (e.g. I need you to let me know when plans re. communication change, I need you to not let me hanging for 8 hours unannounced,) don't exist so you can potentially change the other person's behavior. They exist so that YOU know what YOU will do when those boundaries are crossed, e.g. leave the situation, call the whole thing off, and acknowledge he is not the right one for you, now or maybe even ever.
It's not about him respecting your boundaries, it's about YOU respecting YOURS.
Not saying this is easy, even harder when PTSD looms as the ever-handy excuse, but if in any way possible concentrate (very clearly define!) what it is YOU need/will not waver on/absolutely demand before anything else, and then stick to it with actions of your own - no explaining, no pleading, no back-and-forth. Even with PTSD in the picture, we should never be asked to compromise on our core needs based on mutual love, trust, and respect.