This is a tough time for you, no doubt about it, but I don't think this situation has to be hopeless. Re: "why would you stay in a sexless marriage" - well, there might be any number of good reasons. Your sex life probably won't live up to your ideals, but it seems like you had made some peace with that before this most recent phase; could you accept that again? If you toned down the comparisons and kept the pressure off her, as well as did a bit of waiting out this new period she's in, it might make it easier to reach that balance or even perhaps a better place than it was.
I guess I'm reacting to the fact that you seemed to think you did have a good relationship, aside from sex, before this hit. Do you still believe that? And if so, why should that have to be lost? Maybe sex is just the weak link in your relationship but there are other aspects of it that are valuable. I know it helps to have a good sexual connection as a point to build from, but I'm not convinced that it's essential, especially if you're open to meeting those needs elsewhere. I do know though from personal experience that trying to build a connection and feel comfortable while feeling sexually pressured is counterproductive.
Others asked what you want, and that is certainly something you need to think about. Also, do you know what your wife wants, and is she trying to help you to deal with this? I didn't get any sense of how supportive she is (or isn't) trying to be.