he doesn't blame his actions on PTSD. I blame his feelings as "unwanted, unloved, distressed, anxious, lost, angry, sad..." on PTSD.
I am a sufferer, not a supporter. I want to share something I observed in this statement, and its something I've seen other supporters do.
You are looking for a source - a reason - for his feelings of "unwanted, unloved, distressed, anxious, lost, angry, sad". He is feeling these feelings inside of your marriage, and so he became unfaithful to try and alleviate these feelings. You and he seem to agree on that point.
You are bundling his feelings as PTSD symptoms (that he's having these feelings as a result of the dissociation, depression, etc.)
Please, ask yourself: What if he is actually just unhappy in the marriage?
I'm not saying he doesn't love you, I'm not saying that you've done anything wrong. I'm saying sometimes, when you hear hoofbeats, you should think "horses" not "zebras". People change. Marriages fail. It is a reality of life.
But by being as accepting as you are - and/or by giving yourself the excuse of PTSD - you aren't actually doing what would be most helpful. What would be most helpful would be to get immediately into mediation or counseling and start talking about these issues. Because it's very possible this is a mental health problem - but it is
equally possible that this is a relationship problem.
Besides: the mental health part is something he does need to do on his own. But the marriage part is something you
must do together. Yes, it's really scary to think that your partner might not really want to be in the marriage you want to be in. But wouldn't you rather try now to give it a chance? I can almost promise you, if you don't use this as an opportunity to develop ways of being completely honest with each other your marriage probably won't survive his issues, whether they are mental health, PTSD specific, or whatever.