NEED ADVICE ABOUT talking to my boyfriend about my past HELPPP

AlI • Married ☺️
I cried the first time I had sex because I was sexually assaulted when I was younger my boyfriend was so supportive he is my first EVERYTHING and I love him I want to talk about what happened when I was assaulted but we only see each other on weekends so how do I bring it up? I'm 15 and he is 16