MJ, I second the recommendation to go to therapy to sort this out for yourself. I think the right therapist can help you a lot.
My heart goes out to you, your family, and your community. I hope you all find paths to healing.
I know this is difficult for you, (and counseling may help with this) but try to remember your mom is as hurt by this as you are, if not more so. She is embarassed to face her friends; you mentioned she is even ashamed to go to church. (That doesn’t say much for her church community, IMO they should be reaching out to her.) She is also a victim of this. I know it’s frustrating for an adult to not know how to do things for themselves, but she is most likely in a kind of shock - a “maybe I’ll wake up and this will not have happened to ME” kind of thing.
In this kind of situation we all too often forget the children are not the only victims, although they can possibly be the most damaged. EVERYONE close to the person who commits this kind of crime had “why didn’t I see it” or “why didn’t I say something” moments. Sometimes their friends turn their backs, as if the spouse of a abuser is somehow also guilty. Or they just don’t know what to say.
You are being so strong; it takes a special kind of person to handle what you are going through. I am glad being able to talk about it here helps.
I’m so sorry about all this, Mint Julep. You’ve had a whole lot on your plate lately. Take it easy on yourself, and go puke in whatever bathroom makes you feel the most comfortable. 
I think you need a sanity day too. Not only do you need a break from all the negative, frightening, stressful things, you also need to remind yourself you can take care of yourself. You may be particularly fragile, or almost anything else. Look out for yourself, be a little protective, listen for signs, whatever you can think of to give yourself breathing room. Be thoughtful of the ways you might be hurt. You are one of the victims here – a different kind but still a victim. Keep talking to us, we’re pulling for you.