@boingg Firstly, hugs &
for your situation.
I met a fwb in 2019 who's previous partner couldn't perform PIV due to various operations that left him without all of the necessary equipment. Before he passed away, they had developed a satisfactory sex life where they experimented with toys, and other methods of pleasure (oral, masturbation etc). I was her first PIV lover in six years (!)
Short answer is that you do not have to have a completely sexless marriage, if DH is willing to put the work in, but you absolutely need to talk to him about all this, and get him on side.
If you don't think you can survive without PIV, you could also discuss an open marriage, but again, he will absolutely have to agree, and it could put an enormous strain on your relationship, but it might work for you both. I'm not going to suggest an affair.
Communication is, as in most relationships, key. Think about what you want, talk to him about what he wants - be open and honest with each other - it's the only way you can work something out that will suit you both.
Good luck!