My wife and I have been married for 40 years. It's been sexless for the last 25 years. And by sexless, I mean - nothing. No touch, no sex, no hope of sex. The subject of sex became a PTSD trigger. She was broken when me met and that gradually crept to the foreground, despite every effort both of us made to turn the tide. There is no blame to be parsed out here. She is the only woman I love and the only one I have ever loved. I will never, never leave her.
The lack of sex crippled my own sexual identity to such an extent that the stress made me sick. It's contributed to the congestive heart failure I live with today. People who are outside of our relationship are quick to suggest (as some of those in this thread have) that I should shit or get off the pot: If I can't handle it, i should walk out of the marriage. Those cynical, disrespectful comments invariably come from women who apparently feel offended that such a lifetime disappointment even exists. These people are clueless, ethically lazy and intellectually dishonest. They elect to ignore pain when they trip over it, because for a male to suffer pain in a relationship doesn't comport with their world view.
In my case, after years of attempting to discuss the situation (and triggering a response that at times became violent), my spouse eventually became healthy enough for us to have an honest conversation. I asked for her understanding, for her to accept that a sexual identity was part of my very being, and that the loss of it had done me harm. I acknowledged with respect that her PTSD from prior events (before we met) truly prevented her from participating in sex at any level. I accepted that without reservation and went to pains to make that clear.
I asked for her support and permission to find a source of sexual relief outside our relationship. With trepidation, she gave me that permission. After that happened, an interesting thing occurred. Although I had believed I had put all this behind me, I still felt an enormous amount of anger, rage and pain fall away as if they had never existed. Our life and relationship has become far better than previously. We have rediscovered each other's sense of humor that seemed to have been lost. And this has happened without my having taken advantage of her permission to find a FWB.
So think about working this out with your spouse. Consider couples counseling. If nothing else works, think about the approach I was able finally to take. None of us knows what the future may bring but life is much better than it has been for years without resolution.