How can I tell my therapist about my kink?

(23M) I've been going to a female therapist for almost 4 months. She was my therapist when I was 11/12, but now she attends adults only. We talk about my problems with girls, life and stuff in general.

There's one issue that I always wanted to treat with someone face to face but I've never had someone to do it. I like to wear and use diapers, pacifiers and act like a baby. It's something that I hate I like, it disgusts me, but I never told this to anyone, only a few people online in an ABDL server (using a nickname). It's my deepest secret and I want to tell it to my therapist but I don't know how.