Is my friend wrong for wanting to tell my mom?

Basically I told my friend that I got sexually assaulted, and she asked who knew and I told her that only her and another friend knew. She said “either tell your mom or I will” and she was dead serious. Telling my mom would do absolutely nothing but hurt her at this point, since this happened 3 months ago, and it happened while she was out doing a quick errand, and I think my mom would blame herself (I had a boy over). I get what she means that it’s something my mom should know, but I don’t think she should know, and even if she should I do not think it is my friends place to tell her when I’m not ready.