Trigger warning

When I was 14, I was raped by my boyfriend at the time. It happened multiple times in multiple ways (vaginally and analy). I've never told my mum, although the I have told my best friend, therapist and current boyfriend. 
I'm almost 18 now and I'm struggling with this secret. I don't want the cops involved. I'm scared my mum won't believe me and I don't know what to do. (My mother and ex boyfriend are still in contact and talk on occasion.) 
I don't want to tell her just because I don't want to upset her but I feel like I should? I don't know. I need help. 
Anyone please. 😓