Should I be marrying someone when we have problems in the bedroom?

Okay, please bear with me on this one, it is a difficult situation to explain but I’ll try to put it as simply as I can. I really do need someone’s help and can’t ask any of my close friends or family. My partner and I have been together 19 years and last year he proposed. I said yes and was over the moon. We got together quite young and it took us both a long time to feel financially stable and mature enough to be ready for marriage, so the length of time never bothered me. But since the proposal I have started having some doubts and these have been brought on by problems in the bedroom. Around 4 months ago, my partner went through an extremely harrowing experience where he was the victim of a male on male sexual assault (he is heterosexual). I won’t go into details but naturally it has been an ordeal and one I am fully ready to stand by him in. Of course, I expect this would cause problems in the bedroom but the problem I have lies in the fact that we were already not having a great time in the bedroom prior to this - sex has been few and far between - once a month if we’re lucky and I was already feeling like things weren’t great. I chalked it down to having been together so long but I’ve also put on a lot of weight over the years and having an under active thyroid hasn’t helped with my own capacity to feel good in bed, and I’m sure it hasn’t helped him either. In any case, it had been a few months of trying to have sex and it failing for him. He blamed anxiety medication that he said made him feel numb down there when we had sex. In my own head, I think it’s more to do with the fact that he is no longer sexually attracted to me in that way - I know he loves me deeply as a person and we are the best of friends, but there are just too many obstacles. Now that he has gone through this harrowing ordeal, we are no longer having sex at all and while that is totally understandable, I am left in a position of fearing for what the future of our relationship looks like. If sex had been normal before the assault, I would be barrelling ahead with the wedding in the faith that eventually we will overcome this, but since things were already bad, all I have is his word to go on that he still finds me sexually attractive. He is a good man and I know he would never say if he didn’t because he loves me and wouldn’t want to hurt my feelings. I don’t want to get married if our relationship is nearing an end sexually but Given what has happened I don’t want to bring it up with him or push him about it as it might be too much pressure and I can’t ask any of my family because he doesn’t want them to know about the assault. What should I do?