I would not have surgery in order to appease her or prove you love her by sacrificing your body, especially since she threatens to leave you regularly. This sounds like some sort of manipulation or punishment for her dislike of your previous porn habit.

She should not have access to your work accounts. That is probably a violation of your company policy. When you say that she changed all the passwords on the home computers, does that mean you no longer have access to them?

Her behavior sounds very controlling and scary to me. The copper IUD is a non-chemical, non-permanent birth control option for women that lasts 12 years or so and can be undone at any time. Maybe she could explore that if she is afraid of pregnancy. If she did that for a year and it really did improve your sex life, you could revisit the vasectomy.

Maybe you could point out that men with vasectomies are pretty popular with single women.