If my wife makes more than me and we're thinking about divorcing, would she have to pay me alimony if we both have 50% custody?

Alimony and custody are two different things.

Alimony is also called spousal support.

Support is child support.

What State? Spousal support is a matter of comparing assets and what each person takes from the marriage.

Usually there is no child support with shared custody, so I don't think that's possible.

You need to contact an attorney to be sure, but I was under the impression that if you were working and were able to support yourself and there wasn't a huge difference in salaries, that you would not get spousal support.