Step mom to 12yr old child on spectrum- help

[Mamaoflittleangels]

I am a single mom of 2 kids (5 and 8) and my partner moved in to live with us over a year ago. Last year his ex went off the rails and his 12yr old son who has autism and ADHD came to live with us.
My kids were so excited to have him around full time and I threw myself into being there for him. But, he is very difficult to deal with at times. He can be very blunt and hurts the little one's feelings often. He lies a lot and hides things on purpose. He will physically push people out of the way if he wants to stand or walk where you are. He hums constantly (which I know is a trait), will not eat anything that is not deep fried and refuses to do anything other play video games while jumping around.
Since he has moved in, my little ones have picked up things like swear words, being rude and slamming doors and they will even hum sometimes too. They have started to refuse food like he does and I am about to hit the end of my rope. I feel like a prisoner in my own home and when the kids get hurt or upset by him we usually take refuge in the bedroom.

help.

Does he see any professionals/therapists that might be able to offer some support? It seems like he’s gone through a big change moving and it’s a big change for the rest of the family too. I would reach out to any of the professionals he’s working with for some ideas on strategies, etc. You might need to narrow down what things you want to work on first, what things can wait a bit and what things you might just let go as part of what autism is as going in on everything at once would be pretty overwhelming for you as parents and probably overwhelming for him too. Maybe starting with the pushing people out of the way thing could be a good starting point. Teaching him to say excuse me and/or walking around people instead.

@Lemonzide

Does he see any professionals/therapists that might be able to offer some support? It seems like he’s gone through a big change moving and it’s a big change for the rest of the family too. I would reach out to any of the professionals he’s working with for some ideas on strategies, etc. You might need to narrow down what things you want to work on first, what things can wait a bit and what things you might just let go as part of what autism is as going in on everything at once would be pretty overwhelming for you as parents and probably overwhelming for him too. Maybe starting with the pushing people out of the way thing could be a good starting point. Teaching him to say excuse me and/or walking around people instead.

Thank you for replying!

He doesn't see anyone other than the paediatrician at the moment. I have brought up the idea of a psychologist who specialises on autism to my partner but he is so over whelmed and emotional that we end up fighting all the time. My step son has been living his whole life without rules or boundaries and as an only child. Even asking him to have a shower is enough to trigger a fight between my partner and him. I fear my relationship won't survive this...