Unfortunately your SO lied, maybe not outright, but at least by omission. In my experience, when someone handed me a letter it was because they could not open their mouth because of shame or embarrassment. In the end it does not matter why, because it happened. I received a diary and could not finish reading the damn thing.
If you are not sexually compatible then you need to find a lover, stay married then divorce later or just get it over with and divorce. Don't string it along and make it worse for the both of you.
Hell, I was in a relationship involving group sex, toys, and other perversions. My SO was clearly bisexual and it still did not work. My SO decided to become a lesbian and felt that I would never be pretty enough. We were suppose to transition together, I belive that my SO decided not to transition.
Instantly incompatibility and now that I look back I could never have sex with a ftm. I just could not. It's best that we went our separate ways.
While I am not a cis woman I understand your situation.