So me and a guy (who my best friend knows and is friends with ) kiss and do a lot more, but she only knows that we kiss

The only reason I haven’t told her what we do is that I keep things close to me and I like things to be only known by me, I don’t fully trust people, my best friend is the person I trust most and I feel so bad for not telling her stuff but I can’t help but feel like she’d judge me

I also her uncomfortable really easily, and I can’t hide it because I blush at literally everything

I was just wondering if you think it’s a good idea to tell her or just wait till it comes up by it’s self?