He supported her through medical school but she has found someone else she’d rather be with and now lives in their marital house with her new boyfriend. He wants her to pay him alimony so he can return to school while she wants him to pay her more money to complete a divorce he doesn’t want.
There is a lot you haven’t said about the way this relationship has been going and how it got to this point.
There’s an enormous amount of anger in this relationship, and much of it is understandable. But, being understandable does not make it right, nor does it mean this marriage can survive.
The two of you have grown apart. You can either spend a lot of time fighting the situation and growing more bitter by the hour, or accepting that these things happen (and they do, constantly) and follow your friends’ advice.
Spending money to get alimony from her may cause more pain and bitterness than you deserve. I also don’t understand why you would be paying her $28k to end the marriage if you’ve been supporting her through her schooling.
It’s your life so it has to be your decision as to how you deal with this situation.