I'm confused why you went to therapy. Was this requested if you? This fetish is not uncommon & certainly not a "disorder."
So now your wife knows of your kink. I wouldn't dwell of things in the past. You've put all your cards on the table. Now you need to know from her if she wants to continue in this marriage & what arrangement will make it work for you both...& your child.

Maybe you need to come up with a schedule so there is open communication about where you will be & why. Maybe she does not wanto know the details. Maybe she does. You'll need to ask.
I know many marriages where one partner plays outside the marriage & the other does not. But there are boundaries put in place to make them both comfortable about the arrangement. I've talked to some that use the "don't ask; don't tell" method & it works for them. Some even make schedules around holiday time & what to do in case of an emergency.

I think if all this is out in the open & discussed in detail with your wife then a weight will be lifted off your shoulders.
Many will say, well have your wife cane you, but there's so very much more to it than that. The whole bdsm dynamic & some that can't be explained or substituted.
I've asked my husband for spankings & all I've gotten is a tap on the butt leaving the bedroom. What I want he can't give me.
Wish you luck!