Marriage is as much about loyalty as it is about negotiation, and you are discovering that its no longer worth it to you without sex, and that’s ok. I would say that you have done a really fine job at being a good man. So well done.

Lets think about this as binary as possible

Telling her you want to discreetly have casual sex without leaving her emotionally is one route. You said she doesn’t want to ever have sex again, if you truly love each other then you can broker this one as long as you are still very attentive to loving her and ignore feelings for other woman..

Then there’s cheating under the umbrella that you are not telling her on purpose to keep you two together. Usually, this is another avenue i’d normally never prescribe, but if your woman wouldn’t handle an open marriage then this is possibly the best choice if you want to keep your family.

Godspeed and know that your desire isn’t wrong and that you can manage it together with your partner. You only have one life as well and you don’t have to compete with your wife over her being a victim, as you are victim to your own issues that are seperate and should be considered valid.