Guilty

Is it bad to speak up when something is bothering you? I never trust anyone to tell this specific situation to (I haven’t been raped or anything) but it’s a weird & rocky situation involving a fam member . & I wanna tell my Bf because I trust him & we are close but it’s not something I can explain otp so I told him I’ll explain in person and he’s really anxious like he’s already weirded out by that person already so he really wants to know and he’s upset about it that I’ve been keeping something away from him but he wants to understand the situation but I told him no wait till I see him tomorrow in person regardless of him being upset or anxious. Anyways i feel kinda guilty that I’m letting this secret out because I’ve been told so much not to say anything although I only want to tell him (nothing to get police involved w etc) so idk what to do. I want to tell him but its like something is holding me back I dnt want him to think I’m weird or that I am just like going through all these issues or scare him away even though he doesn’t show me those kind of traits.