I feel like my dear husband (who I love still, despite what he has done) must be so very tormented to have done such a thing that he really needs care and support.
Bella, I understand having compassion for him and still loving him and so forth, however I believe perhaps you are trying to excuse his behaviour by saying he is ill. As I said in private, perhaps it is easier for you to think he has done this because of his illness, perhaps it hurts less and offers you an explanation?
I will repeat a bit of what I said in private. As you know my husband also cheated on me. He was also ill, suffering from combat stress and alcoholism. We had been married 6 years and had 4 children together. However
I had no pity for him. None. He was in the wrong, regardless of being ill. He needed to do a great deal of work upon himself to get me back: he relocated, changed jobs, quit drinking entirely, and went into counseling. I would not have accepted anything less. My love for him did not change the fact that I would not permit myself to be treated in that fashion. I thought of myself and my children first, him second.
Bella, perhaps you feel you are being kind by having compassion for him. However, pity or sympathy does PTSD sufferers absolutely no good. In fact, it is a form of enabling, and will only make them worse. You are in essence saying that because he is ill he cannot control himself nor make his own choices and decisions. That is incorrect. PTSD does not make him a child nor mentally incompetent. Additionally, if you "forgive and forget" immediately with no consequences, he will have learned he can do whatever he wants with you and get away with it.
I could be incorrect, however - from everything I have read, I am concerned that you are forgetting yourself in favour of his needs. You are also important and you need to develop a strong sense of your own self-worth, apart from him. If you do get back together, you will need to have confidence in yourself. He will always have PTSD and that is not easy to live with. You will need to be strong.