Feeling Hopeless - child has become the bully

Maybe this is just a vent, but I feel like I've drained all of my resources.My son is 11 (almost 12) and in 6th grade. He has had a crappy life. His dad and I (step-mom) share equal time joint custody with his bio-mom, and she is just an absolutely terrible human being. She has done nothing but take advantage of my son since he was born and treats him worse than the dirt under her feet. She constantly ridicules him and makes fun of him and blames him for everything bad that happens in her life. She has 3 younger children (and currently pregnant), and ever since the first was born (when my son was about 6) she has made my son care for them because she can't be bothered with it and blamed him for anything bad that's happened to them while he was supposed to be watching him (2 of them have been diagnosed with autism and need extra care). On top of all this, my son has ADHD and about zero self-esteem. While we would love for him to be with us full time, we don't have a lot of money so we can't afford better lawyers and despite multiple reports from his school counselors, his therapists, and his psychologist, CPS has only had a couple home visits and says that they can't find any reason to remove him from the home.Because of this, he moves where she moves and he's been in a new school every year. He also has to deal with her getting a new boyfriend every couple of months (she's currently living in a single-wide trailer with all 5 kids, her sister and her kid, her current boyfriend and her ex boyfriend) and most of them are not nice at all to my son.We try to make our home as kind and comforting to him as we can (we do still have punishments when he is in trouble - no games, extra chores, etc.), however there isn't much we can do when he's with his mom or at school. We found out a couple of weeks ago that there was one point where he tried to cut his wrists at the end of the last school year - his words 'because I want someone to see how I feel when I'm at mom's' - but couldn't go through with it. Now school has started up again and we've already had tons of calls saying he's bullying random kids - calling them names for no reason, kicking in bathroom stalls while students are using them - and I just don't know what to do. We can't let him treat other people this way, but at the same time I know he's looking for some kind of power over something, anything, in his life. I just don't know what to do. I'm feeling so helpless. via /r/Parenting https://ift.tt/2Lp1Rxv