I think I'm not going to buy tickets for my friend's husband and their son.
Why don't you want to buy them tickets?
I just want to ruin his birthday gift
Wanting to ruin your friend's birthday isn't appropriate behavior. Instead of trying to ruin that gift, examine why you feel that way. If there is an issue between you and your friend, try to discuss and address it rather than behave in a way that will negatively affect your relationship.
I wish he was dead and I'm going to make his life hell forever.
Why would you be so mean towards your own friend? You ought to change your attitude if this is how you treat your friends.