I am sorry you are going through that. It's terrible and complex with no simple answer. I'll share my approach to a similar situation. Maybe something in there will help.
My husband sometimes says things that he is feeling in the moment but doesn't necessarily mean in the big scheme of things. So I wonder if that is how your husband really feels all of the time. I mean obviously, it's not an ideal situation for him to not have sex. I can see how he could feel like he does not have the relationship he wanted. He is also experiencing a loss/grief because he probably did not anticipate having a sexless marriage. Regardless, he needs to seek his own therapy because its very stressful to have a partner with PTSD. It's not your job to heal his pain. It's HIS job and he needs to seek the help he needs.
I personally refuse to purposely do anything that causes me to disassociate unless I'm doing it as a form of exposure therapy, have a certain comfort level with it or I think it will benefit my healing. My perspective is that it is my husband's job to make sure his sexual needs are met. He can take care of things on his own. We have a good relationship otherwise and I believe him when he says he has no interest in cheating or ending the relationship.
We have an understanding that I am the one in control and I am the one to initiate any physical contact. I need this arrangement to feel safe. Since we have had this arrangement, my anxiety level has decreased dramatically and my sleep has improved.
Our plan was/is to do the exercises in a book by Wendy Maltz: Dead Link Removed. The problem became that when I become triggered, he gets very stressed and sometimes takes it out on me and is unable to be supportive due to his own stress. If I am going to be physical, I need to be able to trust and feel safe. Therefore, he has finally realized that he needs to go to therapy to learn basic coping and stress management techniques. So for right now, I don't do anything I don't want to do unless I personally want to do it for my own benefit. Eventually, I will have us do the sexual healing exercises in the book or something similar. But I need him to be able to be sensitive if I get triggered.
My own healing and well-being is my top priority. I'm not saying I get everything I want. However, I have a right to basic human needs like a feeling of personal safety and I will no longer compromise on that. Sex is a basic human need too, but I need to focus on my fundamental needs first. It's like putting the oxygen mask on yourself first before trying to help someone else.
I used to disassociate in order to perform sexually. Once my condition got worse, to the point that my health was plummeting I realized I can't sustain that. I need to take care of me.
