Salam Bro,
I am sorry that you are going through this, its pretty hard situation, I pray that Almighty Allah guide you to do the right thing.
Here are my 2 cents,
Your married this girl, she gave all herself to you, in the most deepest sense, and that means you are responsibale of her, wether she was healthy or sick, so just because she is depressed and been acting bit weird lately, does that mean you can divorce her? we all get sick and act weird that doesnt give our partners the right to divorce us.
Have you ever thought what will your wife do if you divorce her? wats gonna happen to her?
If you divorce her just coz you mom wants you to do, then you are doing injustice to her, and Allah doesnt fogive any kind of injustics commited against eachother. And you have to face her on the day of judgmen bro.
You say your mom is sick, what high BP? or sugar? Its NOT your or your wife's fault, call her and tell her to stop worryin otherwise it will harm her health. This is her way of pressuring you to follow her wishes, bro, wrong is wrong no matter what form it takes.
Last thing, why is your wife depressed? Get her a professional help, thats YOUR DUTY, abandoning our husbands/wives at the time of need is unislamic.
Wassalam
