I'm glad SS is in therapy, that was going to be my first recommendation. I'm not really sure what behavior is normal for a 10 year old kid, but I don't think I ever did anything like that at that age. If he's not going to do his homework then he doesn't get video games or TV or heck even junk food, period. He can scream and cry all he wants but there's only one way to get his games and that's by handling his responsibilities first. I wouldn't reward negative behavior. It sounds like he's used to getting what he wants without having to earn it first? Time for a new dynamic, I say. I also don't know if he has any learning disabilities or attention issues, etc. In which case I would consult a professional because I don't have experience with that.

Also, it's not all your responsibility. I'm not sure what time your SO gets home from work, but he should 100% be helping and supporting you in this. He should also be grateful for all your effort, not taking it for granted.