I am very sorry for your situation, very tough one.

This maybe a silly question but,

Has your relationship and marriage with her ever been a " healthy relationship" by that I mean, loving, caring , respectful? and things like decision making together? Agreeing on the specifics of taking care of finances, what is a need versus a want. Everyone needs a " want" every blue moon.

Maybe she is just immature? maybe she is overwhelmed with you always gone for school and her taking care of the baby.. lonely maybe? I am not saying that excuses her actions at all. Just a thought.

If your marriage has just declined to resentment and disrespect ? Or Has the relationship never really been one of mutual respect and understanding ?

Both problems can be overcome, will take a lot of work, no quick fix sad to say.