What should I do? Need advice PLEASE!?

I have stopped talking to my mother for at least 6 months and I plan to not talk to her again. She is a HUGE drug addict, mainly coke and heroin. She is also an alcoholic and into meth. The funny thing is, you can't tell. She is a middle cl person that works as a medical istant at a pediatric office. She hangs around some of the smiest people in the bad parts of town. I unfortunately had the opportunity to witness her actions growing up. She used to make me wait in the back allies tucked away under the penger seat at 12 AM. She also took me into bars and crack houses. I obviously was abused both physically and emotionally by her and her ex-boyfriend. She is 42 and lives in my grandmothers house (failure to launch). She also abuses them, but my grandparents won't do anything about it. She is their only child (they lost their first a couple days after she was born). In elementary school and high school, I reported my mother, but it back fired. My grandmother worked in the administration building for the school district and she pointed her finger at me. They took her word for it since she was an "upstanding member" of the district. No one wanted me to talk. After I moved out at 18 and started my own family, everything has been great! I'm really happy now that I don't have to endure the crap and secretive lifestyle anymore. I did talk to my mom though every once in a while. I figured since I moved out, I could get along with her, but she only continued to talk to me and swindled a couple thousand dollars out of me. She told me that she lost $500 in a store when shopping for MY christmas present. I knew it was BS so I didn't talk to her, but she kept crying to me on the phone that she wouldn't have any money for my siblings presents. Of course, I felt bad and gave it to her. I then found out she told my nana and a few other people the same story and racked up a lot of cash from everybody combined. I stopped talking to her when I found this out. I feel bad for not talking to her because she is my mother, but at the same time, I know I can't be happy unless she is not in my life! Besides, she complains about my kids all the time, even though she has 4 kids of her own, she can't stand either one of us. Thank you for reading this, I know it was long:) My question is, should I talk to her? Or should I leave her to be her own demise by her screwing up her own life? Bible quotes are welcome! Thanks a bunch:)