I feel like I want to make my partner return his new computer
Why would you make him return his computer?
Because he bought it for himself instead of for us.
You don't have a right to force your partner to return his computer even if he bought it for himself. People are allowed to make purchases for themselves and you should understand that.
I hate his fucking face.
You hate him because of his new purchase? You need to calm down and buy something you want so you can forget about his purchase. Problem solved!