If you work does your employer have any benefits such as an employee assistance program? Most jobs I’ve worked at (grocery store, Costco, and a school district) partner with companies that offer assistance through an EAP for free and confidential help like counseling sessions, financial planning sessions, nutrition sessions, etc. it might be worth looking into to see if your job has a similar program/benefit.
There are also likely local organizations that specialize in domestic violence and/or sexual violence that offer free or low cost assistance to survivors, that might be a good place to start. I agree with what @Grazydol8 said, that a counselor, therapist, or advocate may be able to help you figure out how to share this with your mom and what to say so that she can support you the way you need. They may even be able to help you facilitate the conversation.
Although a completely different situation, I did see someone speak about their cancer diagnosis and how when they told their mother about it she kind of prefaced it by saying something along the lines of “I’m going through a difficult situation right now and I would like to share this with you, but I know you’re going to have a lot of feelings about it. I really need your support right now and I cannot be the one to help you process how you feel about it. I am still working through a lot of difficult feelings and really cannot be the person you work through yours with. I just need you to comfort me right now, I can’t be the one to comfort you in this situation.”
I’m really sorry youve experience this. I’ve attached a link with lots of info and resources for survivors {gBSZQaNd5}
Wishing you all the best 💜