If you divorce him you only get half of his money. If you kill him you get it all. Now if you could get alimony or child support, you have to consider both of those. Of course child support ends at some point, and alimony can as well if you re-marry. If he has a good amount of life insurance, that can also weigh in. And there are variables as well, like if you keep him alive you have to keep putting up with him in some way (if you're getting alimony, if you have kids, etc.). If you kill him you are done and can move on.
Clearly, I think your best option is to kill him.