I think an SO of 6 years should know everything about your CDing including how it started and whether or not you still get turned on by it. Obviously you should tell her the extent of your dressing (just underwear, full out presentation with wig & forms, etc) and how often you like to dress (everyday, once a week), and how important CDing is compared to her. Be honest.
I don’t think you can dictate who she tells. It will be her choice to tell whoever she is comfortable with sharing that information.
If you want to see a shrink, go for it. You could invite her but not insist that she joins you.
