Wanting full custody
I have been married to my DH for almost three years, and I have a SS (11) and SD (7). I love them more than anything and they are wonderful kids. I couldn't ask for more. However, their BM is a NIGHTMARE. She has been unbearable from the very beginning. She absolutely believes the world revolves around her, and she is perfectly willing to hurt the kids in one way or another to get what she wants. In her mind, the kids are simply a reflection of her (she pretends to be supermom in public, on the PTO, signs the kids up for every sport, makes sure they have all the latest electronics and name brand clothes, etc.) But away from the public she is a horrible person and mother, and the kids are suffering for it.
Backstory.... BM is in her 30s and lives with her parents. Both of her thirty-something brothers also live there. One brother is a convicted felon and is in and out of prison for drugs and theft. Neither of my stepkids have their own room there. SD sleeps with BM and SS sleeps where he falls. They technically have a bedroom that has their clothes and stuff in it (shared) but the whole family are hoarders, and the room (along with the rest of the house) is packed too full of stuff for the kids to sleep in it. There is not consistent discipline there, and the kids basically do what they want until BM gets pissed and then she yells and screams and hits. They do not have a bedtime, and I've often seen SS active online past midnight on school nights. BM does not help them with schoolwork, and does not play with them. She wants them to stay out of her way. BM works occasionally sitting with an elderly woman in her home, and is in nursing school.
We currently have joint custody of the kids, switching off every week. Here, the kids have their own rooms, their own space. We have an established set of rules, and the kids know what they are, and also what consequences they face for breaking them. During the school year, the kids know their schedule. Homework as soon as they get home, no playtime or tv until it's finished. SD is in the bath by 7, and in bed with her bedtime story finished by 8. SS, a little older, has his shower at 8:30, in bed by 9. We try to do things with them, like fishing, biking, board games, etc. DH works road construction and I just finished nursing school (still applying for a job.) Basically, we try to be involved with them and give them a structured but caring environment they don't get at their BMs.
This has always been the problem, but lately, it's gotten much worse. Specifically for SS. BM has always treated SD better than SS, and both kids notice it. When SD was 5, she told us that she wanted to be just like her mommy, and treat her little girl really well and her little boy really bad. It's THAT noticeable. SS can do nothing right as far as BM is concerned. She's always screaming at him, and telling him he ruins everything. SD knows that she will not get in trouble for bothering or hitting SS at her mothers, so she torments him there. If he tries to tell on her, BM and her mother tell him to get over it. If he retaliates, he gets beat with a belt. He can't win. BM has admitted to shoving him down in a pile of boxes before, and last year let him stay with us full time for a while after DH found out she had hit SS in the face with a closed hand. That lasted about a month before she got mad and changed her mind. SS is miserable up there. He is terrified of BM, and he wants nothing to do with her. SD thinks the sun shines out her ass. We've tried talking to BM about easing up on him, but she does not think she is the problem. She's convinced he is just a bad kid. She took him to therapy for a while, but she always sat in the room during the sessions, and SS was too afraid to say anything in front of her.
Shit hit the fan on Mother's Day. We normally switch on Sundays, but BM gets them on Mother's day. SS texted DH about 1pm and begged him to come and pick him up, saying things were bad up there and he wanted to come here. He said that BM had told him he ruined her mother's day and beat him with a belt. DH called to talk to him, but BM wouldn't let him. So DH, knowing he couldn't just kick the door in and cause a stink, called the police and asked them to check on SS. We arrived right behind the officer. Nothing much came of it, except BMs mother saying that SS got beat for hitting SD with a pan, and that he "needed serious psychiatric help because he was out of control." While SS was standing there. The cop did talk BM into letting us take SS home, while SD stayed behind. SS admitted that he had hit SD, but that she had been following him around and kicking him and BM wouldn't tell her to stop, and he got beat with the belt while SD did not get in trouble. The next day, BM showed up at school and pulled SS out of class and told him that she was not taking him on their planned overnight trip to a waterpark that week, and that she was cancelling the pool party that she had reserved for him for his birthday on Saturday. Needless to say, SS was crushed and had to tell his friends that his party was cancelled. The next day was his 5th grade graduation, and she told me there that if I wanted to pay for the party, I could, but she wasn't going to give him a party now. So I did. I went to the facility, changed the reservation to my name, paid for the party, and gave SS invitations to give to his friends. We hear nothing from her until about an hour before the party, when she calls and says that she is going to show up and take pictures. DH tells her that he doesn't think this is a good idea. He said that she wanted to cancel the party and try to punish SS by ruining his birthday, so she didn't need to be there. She tried to say that it was her party, but DH said that it was our week, the party is in our name, we paid for it, and she has no right to show up. She asked to talk to SS, and asked him if he wanted her to be there. He told her no. Me, my DH and his parents could hear BM through the phone telling SS that if he didn't tell DH to let her come to the party he was going to be in big trouble. She then tried to tell him that she never said she was going to cancel the party. SS starts to cry, so DH takes the phone and told her that she had tried her best to ruin SS birthday because she was mad, and he wasn't going to let her make SS cry. She lied and said she didn't tell SS he would be in trouble, but DH told her he had heard it all, and that we had to go, and if she tried to show up and cause a scene at the party, we would call the police. She didn't show up, but SS could hardly enjoy himself because he was so afraid she was coming.
We really want to try for full custody of both kids, but especially SS, because he hates it there, and she makes him feel horrible. He is a really good kid. He has some issues with expressing his feelings, and he gets angry, but who could blame him? Both kids are well behaved here, they make excellent grades, and they are happy here. But I'm afraid that the court would favor BM because she is the mother. And I don't really know where to start. Do we get a lawyer straight away? Should we take SS to counseling so that his side of the story can be on record? He wants to live here, but BM wants to hurt DH so she refuses. (Even though she told DH's mother that she wished she could just have SD and DH would take SS.) Do we have a solid case? i just don't know anything about going to court for custody, but I want the kids out of there so bad. She's not normally outright physically abusive, but being in her house is detrimental to both kids, especially SS. All of SS issues stem from the way BM treats him, and obviously BM is not a role model for SD, even though SD adores her. Any tips on how to proceed or how much substantial proof we need would be much appreciated. I'm so lost on where to begin, and I'm afraid we will go in unprepared and end up making things worse or losing the kids altogether. Sorry this is so long, I've been bottling it up for years.

crushed
confused
Happy