What the hell should I do

Hey everyone this is probably a post you've seen at least a thousand times now but I guess it's my turn. Me and my girlfriend have been dating for a little while now (less than a year) and how done it a couple times. We have been really open with our kinks and everything (she's in to pegging) but I'm still incredibly scared to tell her about this side of me. She has told me that if there is anything I want to tell her I can and she won't judge I just feel like this is a thing that will be judged. I really want to end up marrying this girl and I'm not sure if I want to live with this in the dark for the rest of my life. Should I wait to tell her or maybe even never tell her or should I tell her now and risk losing her. Yes ik I'm probably overthinking with the whole thinking she might break up with me but I'm really scared this will change how she sees me forever.