Not after 40 years, not after 56 years, not after about any number of years before dementia sets in to fill the gap, will the dysphoria go away.
Dealing with it does not need to be an all or nothing situation. As you may already be noticing, just being able to say the words to another human lifts an incredible burden from you. In time all those years of shame, the decades of guilt over who and what you are begin to fade. Simply by just not keeping it all bottled up to yourself and you alone.
As you already know and feel immensly, none of that shame or guilt will go away keeping this from your wife. From what you said so far, that she suspects, the joking is more of a way to relieve her nervousness over it.
Joking to relieve nervous tension sounds like a better anticipation of shocking news than anger.