Borderline Personality Disorder?
Stepson is an undiagnosed Autistic 11 year old. He's in a special class" at school. He had to move schools due behavior problems. I have 2 of my own kids around the same age. He's violent, kicks, hits other kids. Threatens kids. Throws things, throws tantrums. He's becoming more and more hateful. BM has refused to even consider medication (I also believe he has ADHD). BM's response is that "he's just having a bad day."
He has isolated himself by behaving this way and now has no friends. He never had friends to begin with. His parents always said that he would "grow out of it" when he was younger. He never has.
He tells my son that "his mom is better than me."
When I look at him, he gives me a look that could kill. He despises me. He has informed his mom that he hates me and that he hates my kids (he also informed his mother that he hates her as well). He doesn't listen to me. He wets the bed and also has terrible manners, table and otherwise. I've also on several occasions seen him harm my dog. You're not supposed to lay on top of and smoother a small dog.
Keep in mind it's not all bad. I expect kids to show me respect. They will say please and thank you. They will help out around the house etc. If I give them a task they are not to throw a tantrum. They get a lot of my time as well. Movies, vacations, game nights etc. I even taught Stepson to ride a bike - last year.
DH let's BM dictate medical care / school care etc. Says he would have to take her to court to change that. That there's not a lot he can do about the situation. They are doing a terrible disservice to him by not "labeling him" IMO.
BM has FINALLY said she would like to take him to a counselor. We will see if that actually happens as it's been said in the past. Then I know that SHE will also go and sugarcoat the entire situation and we'll be back to square one. This behavior is NOT normal. His parents divorced when he was a young baby and I have been married to DH since the kid was a toddler.
I am dreading the stepsons visit tonight; hence why I'm here. Just venting as I don't see anything improving. It only seems to be getting worse. 
Wait, I'm confused. How can
Wait, I'm confused. How can he be "undiagnosed autistic"- you can't be labeled that and put in a special class if you aren't diagnosed. The violent aggressive behavior is not ADHD or Autism, most likely - more like a mood disorder or oppositional defiant disorder. 11 is much too young to diagnose Borderline Personality Disorder - but who has decided he's autistic?
Anyway, BM is not doing him any favors, and it's too bad the school hasn't called CPS on her for refusing to get him treatment.
I shouldn't have said
I shouldn't have said "undiagnosed autism" as I was venting. The reason that I said it is because on top of the things I listed, he doesn't make eye contact. Hates taking showers due to the water spraying him. Will develop ticks like flapping his arms or repeating the same things over and over. Things like that.
OK - but if he's in a special
OK - but if he's in a special class, he must have some kind of diagnosis?
Your DH needs to get off his butt and get his kid the treatment that he needs. If he doesn't have a legal right to do it, then take it back to court. The longer he and BM let this go on, the worse of a prognosis this kid has.
I'm not seeing anything that
I'm not seeing anything that says autism from that description and I'm also confused how borderline personality disorder fits in. Also, why are you saying he definitively has something if hes not diagnosed?
I shouldn't have said "undiagnosed autism" as I was venting. The reason that I said it is because on top of the things I listed, he doesn't make eye contact. Hates taking showers due to the water spraying him. Will develop ticks like flapping his arms or repeating the same things over and over. Things like that
Yeah, that would likely be
Yeah, that would likely be autism
Protect your dog!!
I've seen posts like this before where buried somewhere in the narrative is the fact a stepkid is being cruel to an animal. WAKE THE HELL UP! Protect your dog!! And cruelty to an animal is the sign of a sociopath not autism. If I were you that POS would be SEVERELY punished and then would never be allowed in my house again. Just NO. Unacceptable.
He was harming the dog by
He was harming the dog by laying on top of the dog - not necessarily being intentionally cruel. The point was that I don't trust him to make good decisions.
I'm glad you're able to make
I'm glad you're able to make that distinction because theres is definitely a difference between a child being intentionally cruel and not understanding. You're not wrong to not trust him. Also, do you think it could be an impulse control issue? That's an ADHD thing and maybe autism but im not sure - sometimes the action comes before the conscious thinking it through and comprehending that it could hurt the dog.
Regardless, This kid is sick
And no one as BM or BF is not helping. He needs help, they are not getting off there butts to do something, anything.
Your SO is one bad parent.
A lot of mental disorders
A lot of mental disorders have symptoms that overlap. It can be hard to label them. What you do know is that he has behaviors that are unacceptable and he is unable to function in a normal classroom. If the parents are unwilling to address these things, it's not going to be easy. You should talk to your husband about the behaviors you can't live with and about his future outlook if he can't function in society. He needs professional help and consistent parenting. You may be looking at him living with mom and dad for life. Please plan your life accordingly, and good luck. You have a duty to protect yourself, your child, and your pets.