Hi Phoebe I am sorry that you are having a tough time with your son, he sounds as though he has quite large jealousy issues which he is acting out by being angry and lashing out at you and his sibling.
What he is craving for is attention from you, positive or negative. I wonder if you tried to engage him on a different level than you perhaps have been may help. I would in your shoes encourage him to do things with you such as helping with cooking evening meals (making bread, cakes, cutting up veg, making sauces etc), this will give him and you time to chit chat whilst channeling his aggression into something creative. Give him some extra responsibility and praise him when he makes an effort to engage in this manner.
Try to do one activity every day that is between the two of you, it can be something fun or just every day chores, all he wants is time with you. So racing to see who can fold the biggest pile of washing, or helping in the garden.
Encourage him to do something creative that is just for him, a patch in the garden (or in an indoor planter) to tend to, growing veg can be very grounding and rewarding.
Has he a pet that he can look after? Looking after other small beings can help to channel thoughts and feelings.
Try not to engage in arguments, you are the adult he is the child. Acknowledge his feelings without excusing them, so say I see that you are upset/cross/tired etc but we do not behave in this manner, we talk about our feelings. Listen to his acting out, interpret for him, feelings are ok, it is what we do with them that ultimately matters.
If things get too much and he is unable to break this cycle with your help then I would ask the school or gp to help him access play therapy counselling. This would hopefully enable him to learn how to name his feelings and articulate them better as well as allowing him to work through issues of jealousy.
I hope that you can get your happy boy back.