stepmumm, I thought you were describing a much older boy. :( I have a 12 yo and they are stroppy, but they are controllable. It takes the will to do it and it must come from his dad, who it seems to me is backing down from confrontation and leaving a lot of it up to you. My DH does the same.
Ultimately, no-one wants to be seen as the bad guy in their childrens eyes, so they leave it up to the other parent to do the work so they can be the loved one. This is double the issue when the evil stepmother is the other parent. How much easier to let her do all the nagging so you can maintain your hero status.
So...your DH needs to step up and issue the punishment - and the expectation of good behaviour. And I agree with removal of priviledges, and id add on some extra chores as well.
My DS has to:
keep his room presentable
Set and clear the table and help his siblings clear the kitchen
Help in the garden
Bad reports from school or bullying his brother mean he is sent to his room. He has no TV/games console in there. He also has his phone removed. Each and every time.
We also impose a 24hour "screen ban" on all TV/Vid/Games/computer plus phone for bad behaviour. We also have the option of stopping pocket money, and use this if he deliberately breaks things, loses sports kit etc. This month he owes me £5 because he borrowed someone elses PE shorts and lost them on the same day. Now I have to do a trip into town to replace them.
He whinges about how unfair his life is and how everyone else does XYZ. I ignore it.
On the plus side, he gets to do his sport that he loves, he gets time to watch his favourite teen boy TV, play on the computer, eat and drink good food, go out with his mates to the cinema (care of mums taxi). His life is not one big drudge, but we have set very clear expectations about acceptable behaviour and we have set very clear sanctions should he choose to ignore those behavioural guidelines. And these are enforced each and every time.
We do not have a rosy Waltons life, but at least the behavioural standards are in place and clearly understood.