I don't want to go through with my husbands ultimatum for a reward
Why do you not want to go through with it.
I don't think the reward is good enough.
It's unfair if your husband to give you an ultimatum. In a marriage, people should try to compromise and find common ground. It may be worth reevaluating the relationship to make sure that it's still working for both of you.
I am just so unhappy in this relationship and don't know what to do.
Then you and your husband should discuss better ways to get what you want out of your relationship.