Attached Mother how do I stop it?

My boyfriends mother won't allow her kids to grow up. She took them all out of school in the 5th grade and homeschooled them for a week and then stopped. So my boyfriend stopped school at a very young age along with his older brother who was taken out at the 6th grade. She has a 35yr old son who is married with a kid who lives with her. A 24 year old who lives with her who works part time and she cleans his room and does everything for him and the 35 yr old. My boyfriend he is 22 and wants to move out he moved states to get away from them but they followed. The minute we said that we where going to move out she started hating me!! They all say I am taking her son away from him and her grandson because we don't love her anymore. He went in for a very very good job and when he went in for the interview she told him that she hopes he does not get it because then she knows he can move out. She will not allow anyone around his son and his son does not act right. He cries 24/7 and I took him to the park (for the first time) (hes 2) and he did not know what to do. He just did the same things over and over again for 2days straight and then finally started doing stuff and acting normal. The only time this kid gets out is when ever he can get his son away from his mother, or when I can, or if she takes him to the stor. (Thats all he really has done in 2 years.) They only buy crappy food and live in FILTH! There is mold in the kitchen, bugs in the fridge, trash everywhere, and no air conditioner! I made my boyfriend buy me my own kitchen in our room so I do not have to eat in the bugs. She texts him 24/7 even if he is just in the other room and he will only answer in one words trying to just get her to leave him alone for a minute and she wont stop or will start talking about how much he hates her... Now she wants to get his son every weekend (to let him eat candy every morning- he has all 5 front teeth pulled out because they where complelty rotten) and I just do not understand the FILTH they can live in (my boyfriend hates it and so does my son) and how she can be so attached. How can I fix this? What is her problem? Is it because she does not want to let her kids go because she hates her husband and they only stayed together because of the kids. She does nothing for her self at all. Is she scared to be alone and stuck with him?