How do I tell my partner my fetish ? F21 and M24

This is very awkward and I’m very embarrassed to post this but I need to ask since I feel confused. I’ve dated my partner for the last year and it’s been fine. He knows everything about me expect my fetish. I have a tickling fetish and it’s the only one I’ve ever really had. I really wanna see my self forever with him but I’m not sure what to do.

I’m not sure if I should tell him cause I don’t want to keep secrets but I really want to tell him. The only issue is he told me his mom used to do it to him as something bad and I can’t bare that thought of bringing up bad memories. I’m just not sure if I should. Any advice ? I really feel lost right now. Thanks!