My wife once said "We can't control other people's reactions."
Obviously you want and feel that you need to share this part of who you are with her. That you feel you are lying to her.
Mental health is more important than many of us realize. "Tuff it out" is how we were raised as male.
I told my first wife when she caught me hiding under the bed in a skirt and blouse. We talked a bit I thought we were all good but then her later reaction was to have an affair. Which that I believe was the beginning of the end.
Having had that happen I made certain my wife now knew about Joyce before we had gotten too serious.
You never know ... for sure... how someone will react.