Should I call CPS on my mother?

Hello everyone, please understand that I am just looking for advice. I also understand that this is a parenting website while I am only a 21 year old college student, but I imagined that parents may be wiser in knowing how to handle my situation. I appreciate any suggestions.
My mother is 41 years old, has not had a job in 3 years, receives food stamps, and lives on Section 8 housing. Four years ago, she attempted suicide and failed, was sent to a drug treatment facility, was kicked out of the facility, ended up on the streets of NY, pregnant, and using heroin. Eventually, after that whole mess, she came home to stay with my grandma and had my little sister (who is 3 now). I also have an 8 year old brother. She has gotten "better" since then, I guess, but she has been using methadone for 3 years now at a clinic, smokes marijuana, has no car, and when she finds a car to use (my grandmother's) she drives with no license (suspended for parking tickets, I believe.) She does all this with my younger siblings around.
Recently, the father of my sister (same person whom introduced her to heroin in NY) was released from prison on parole for dealing drugs, and my mother basically kicked out the 8 year olds father and moved the 3 year old's father in. He is paroled out of state, as well, and so as far as I'm concerned is living with my mother illegally. He is a felon, and this worries me. He got caught shoplifting (my mom claims) and was sent to a drug treatment facility. He was recently released from there and is now living with my mother and siblings again. After not caring about his daughter for 3 years, he now suddenly seemed to have a change of heart while also needing a place to stay once released from prison...
Anyway, that is besides the point. I have been wondering for quite some time now whether it would be right to call CPS on my own mother. Growing up as her child, I do NOT wish for my siblings to grow up the same way. My mother was emotionally abusive, had a prescription pain killer addiction, and basically left my twin sister and I to raise my brother when he was born. (She would leave many nights until 3 or 4 AM). She has changed a little, but my younger brother tells me he does not want to live there but is afraid to tell my mom because "her feelings will break." He also says that she leaves both of them (ages 3 and 7!) home alone early in the morning for hours at a time doing a "side job" (driving people around, he says), and sometimes he has to get my little sister up and fed. He also told me there is no phone for him to use in case of an emergency because my mother carries her phone with her excessively. When I come home from college to pick him up from my mother's, his room is always dirty and his clothes are, as well; they often smell and are unwashed. He complains constantly that he never has clean socks to wear and that sometimes there is no toothpaste or toilet paper, etc. He also told me that the hot water has been turned off for quite a long time now, which I did not know. He says that my mother boils water and "wipes him down", and that is how he showers. He recently got caught cheating on a test at school, has been doing very poorly in school in general, and is clearly withdrawn (possibly from his dad suddenly moving out, I'm not sure).
My brother's father has moved on, holds a steady job, and is probation for not paying child support to my mother who does not use the money for my brother-which I know for a fact. My mother REFUSES to let him see his son unless there is money involved. He is afraid to file for custody because he is on probation and knows that the judge will probably use that to his disadvantage. He is constantly calling me to ask me to check on my brother because my mother refuses to let my brother speak to his dad. She barely answers the phone for me. My brother did not have clothes for school this year, but my mother made it a point to purchase new Jordan sneakers for the felon, so my partner and I bought clothes for him, as we usually do so that he does not have to go without. Same for my little sister. Over the summer, they came to stay with my partner and I for over a month because I did not trust them with my mother during summer while not in school. My own grandmother (my mom's mom) even has said she was going to call CPS and have the kids live with her (she lives in the same town), but she is 66 and has trouble walking and working.
I do not know what to do. This felon is my little sister's father so I know that this will be a huge factor. I am seriously worried about the well-being of my siblings emotionally, which I know doesn't seem to matter in many courts. I do not think that they are abused physically, but my mother does smack and hit my brother sometimes for not listening and my brother tells me that sometimes the felon will lock my little sister in her room is she acts up. I'm also worried about their safety considering they are left alone and also are living with a convicted drug dealer, even is he one of their parents. I know that if I called, my whole family would know immediately that it was me and all would go wrong basically. But I also know what it was like growing up as my mother's child. She sometimes got violent with us (she kicked my door in and beat me with a broom one time because I would not give her $20, punched me in the jaw another time because I would not give her $15 and then kicked my sister and I out the same day, and I have not been back there unless its to visit my siblings) and she NEVER made us her priority. Knowing what it's like being her child, I'm afraid that my siblings will go through the same as they get older. I am graduating in May and have known since my brother was born that I was going to have to take care of him because my mother has been doing less and less well. She is extremely manipulative and a pathological liar. The only reason I keep a relationship with her is because I know that she will use my siblings against me. I still plan to care for my siblings if I can, as I have a very stable life aside from college with my partner for 3 years, although it is out of the state (I live/go to school in NJ while my partner is out of state). CPS has been involved before because a neighbor complained that my mother was keeping the kids in a house with no electricity for weeks (which she was) and this just reminds me of my childhood, which I don't consider "good" but also not "horrifyingly abusive". However, I feel that my siblings are worse off now than I was growing up. I do not know when it is acceptable to make a call like this. Does anyone have any respectful suggestions?

(Also, I'm referring to my sister's father as "the felon", lol, I apologize!)