I'm going to tell my wife she can't go back to school
Why don't you want your wife back at school?
I don't want to spend the money.
It is good she wants to go back to school. You should not control her if that is what she wants to do.
I would prefer is she was dependent on me
The last thing you said sounds abusive. She needs to be able to do what she wants, maybe you should talk to a therapist about your controlling feelings.