Hi CC - I'm really sorry that you are both going through this. I can only speak from personal experience, I don't know if this will help, but hopefully something will.
I am useless at relationships. I would much rather isolate. I even isolate from myself by shutting myself off from my emotions so that I can be numb to my pain. That said, I have been in a loving marriage for over ten years now with a very patient man, who at times reaches the limits of his patience just as I reach the limit of my ability to cope with my pain.
I don't push my husband away, or my son, however I do feel a real guilt that through me they experience PTSD. I have worked on this in therapy but here's my thoughts that seem close to what you describe. My trauma meant that I will spend the rest of my life with PTSD, sometimes doing well, sometimes struggling. By being married to me, or being my child, these people - who I love dearly - will spend the rest of my life with PTSD. Sometimes they will have an easy time, sometimes it will suck. I can not even tell you how many times I have thought, "the truly selfless thing would be to live alone the rest of my life and not inflict my PTSD on others - especially these most important people in my life."
My husband and son do not want to lose me. I do not want to lose them. And so we ride good times and rough. We have both learnt how to communicate better - although not perfectly. He understands that my struggle with my pain is not a reflection on how much I love him. He knows that when I hug him and get close to him at night when things are particularly rough that it is a huge sign of my love - something I should never have been able to do.
On my part, I am learning to say, "things are bad," or, "triggered," or some signal that I am struggling. We have talked in advance that this does not mean, "I don't love you," it means, "I am hurting and I just don't know how to get through today."
So, my two-cents worth. Have no idea if this is helpful or not. This is just me and I can't speak to your personal situation. However, isolation is very, very common in PTSD - and the reasons above are just a couple. Being a person with PTSD it is so hard to connect to anything or anyone, including ourselves. The fact that he talks to you in the way that he does after he has struggled, and during struggles, speaks of real love to me. Only something really worthwhile would make anyone with PTSD try to connect to anything or anyone.
With deepest respect,
Rain