Sociopath Community

I have the typical nmom and ndad (who is also an enabler to nmom's behavior), but for the past five or so years, my mom created this alter ego type thing. Whenever she wants to say something generally considered offensive, homophobic, or racist, she'll do this super high pitched voice to say it (weird, I know). Then she'll be like, it wasn't me, it was, let's call him John, I don't want to put the real name... And "John" is extremely perverted and makes remarks about wanting to fondle my seven year old brother's school friends. It's disgusting, but I really have a hard time remembering a time when this wasn't a part of my life. Everyone thinks it's funny except me, my sister, and my dad, but he won't confront her about it. I'm sick of people just telling me to "hold on" for awhile. My mom knows about my depression but keeps steering away from getting help since I refuse to talk to her about the problem. Just a few weeks ago, my sister was leaving the bathroom in a towel, John said she looked "hot" and that she should come to "his" bedroom. My sister started crying and told my mom to stop harassing her. Now my mom continues to make her comments all the while making fun of my sister's attempt to stick up for herself. I'm 13.. Just someone help turn my life around :'(