In the mid/late 90s, I was in a horrible relationship, also mostly sexless; it produced two wonderful sons (I calculated that, from the conception of the first until I left, we had sex less than five times. We must have been quite fertile.) so I've no regrets. The relationship drove me to the edge, but I did have a counter-balance: during the 90s, I was a moderately successful stand-up comedian. I was a teacher by day but on some Friday nights, for example, could be found on stage in front of 150 'lively' Scousers, or similar and, in those circumstances, you have no mental capacity to ponder your troubles. It kept me sane, no doubt about that.
I suppose what I learnt from that was that it's necessary to have something in your life that is just for you and you alone, and has the power to take your mind away from the troubles and disappointments which colour your every thought and action. Very shortly after my wife's affair, which was a burden on top of the poor sexual relationship we had, I started to develop another creative outlet, which I won't reveal here in order not to 'out' myself but am happy to discuss privately. This outlet requires significant input from me in terms of planning, execution and what to do with the results. It's something I've built up from nothing, and get very little help with. I do it for me and for no-one else. It takes some time away from my marriage, which is time that I need. In fact, when I'm engaged with it, I forget that I'm a husband, and that doesn't mean that I'm chatting women up, because all of that goes as well. I get a little bit of encouragement from those around me, but not much; it's something that I may just possibly end up being 'successful' at, in five years or ten years, and it will be purely by my own efforts. It gives me self-worth and self-esteem and reminds me of what I am separate from my slightly dysfunctional marriage.
I've accepted the possibility that my sexless state may never change; if it so be, then it will be "the beginning of death", as a character in a Graham Greene novel put it. I'm not for a second suggesting that anyone else in this thread accept their sexless marriage, especially not if you're younger than me (late 50s; the '1964' in my username is not my birth year.) The choices for those in our position are stark: one of them is to leave our marriage and this is something that some of us can't contemplate. I don't think we all 'deserve' happiness. I do believe strongly that we all have the absolute right to behave in a manner which will promote our own happiness, and that those around us have to accept this, especially when it is they who are placing restrictions on our well-being.
What I'm saying is: you've a right to be selfish.