Yes cocaine is very addictive, the reason I’m on this site is because of my partner having got gradually more and more addicted to cocaine and disrupting various areas of his life.
I suppose for your partner he doesn’t have the emotional attachment to be concerned like you, but he also might feel worried to get involved in case he offends anyone, especially if he’s relying on your mom for somewhere to live. He probably thinks he is being supportive to you both by not judging her.
It doesn’t sound like you are being selfish it sounds like you are putting her needs before yours. Yes she is an adult that can make her own decisions but it sounds like they are affecting your life aswell, and it sounds like you can’t make the decisions you want to make.