Background: I have been with my husband and his three boys for 8 years. When we met, BM was more interested in partying then having anything to do with the kids - even going as far as telling people that she did not have children or that they ruined her life. The kids often were not fed or bathed, and often missed school. I almost immediately stepped into the mom role, even before we were married. She is the type who does not want to parent, but does not want other people to know that she doesn't, so she hates me. She has never taken them to the doctor or dentist and has never attended one of their sporting events. We would often receive calls from their friends' parents saying she dropped the kids off without asking. They were typically left home alone or with her grandmother. We now have primary custody and she is not allowed to have weeknight overnights during the school year. 

Over the years, BM has chosen one child at a time and tried to alienate my husband (BF) and I emotionally from the boys. It never lasts for very long, but while it is happening, the child comes home with new clothes, shoes or toys. BM shows them attention that she previously never showed them. They begin to disrespect my husband and I, as well as their teachers, coaches, etc. They are in more trouble at school and home. Their demeanor is so different that we immediately know what is happening and are able to talk to the child to correct it. The most recent was last year, when our youngest, now 12, did everything he could to upset me. His baseball coach pulled him aside and he admitted that she was telling him to misbehave and not listen to me. After the coaches' talk, the child corrected his behavior. The other boys are twins, now 16. One now has a serious girlfriend and BM has become "besties" with her. The child is becoming more disrespectful toward his BF and I. He is doing everything he can not to spend time with his dad and has become extremely defensive of his BM on the rare occassions she is brought up (we rarely talk about her to the children). The sheriff's department and CPS were called on my husband and I by BM with unwarranted claims of abuse. She also tried to claim abuse in custody trial. When the state sent her a letter regarding her unpaid child support, she told the child that she would have to sell his stuff since we were going after child support and the child texted my husband saying that "he couldn't believe he was taking money from his own kid". 

We have always been a close-knit family and I am struggling with this alienation because it has never gone on this long. I am trying my best to disengage until BM loses interest again, but it is depressing when I have been the parent for the last 8 years. Any advice??