Dementia like symptoms

My mom has primary lung cancer with multiple brain mets and has been treated with steroids and radiation to the brain.  Her symptoms have been all neurologicalbeginning with speech, memory and vision problems.  She has now become very confused, angry and anxious.  Having always known her as a very soft and kind person it is very difficult to now see her so difficult and abusive.  I am wondering if there is anyone out there who has encoutered a similar situation and if you have any advise on how to handle things.