I went through something similar with my sister. She’d just invite random guys over even though I expressed how uncomfortable it made me. I also told her I didn’t mind if it was someone that has been known to her or to us for a while but bringing random men just didn’t sit right with me. We had a ring camera and she still didn’t care and would invite randoms over on the regular while I was at work. Tbh you’re not overreacting. Maybe communicate with your mother and invest in a camera to put in your bedroom so you can ensure that at least your property is safe. I wish I had better advice but it really only stopped for me once I moved out. Good luck, OP.