Mom (64 years old) got dementia after her husband went to prison

My moms husband (my step father) got involved in a white collar crime and was charged with 8 years in prison in a different state (it will most likely be closer to 4-5 years). Since this happened three years ago she started developing major cognitive delays and disfunction. She can't remember many names or words, she has a difficult time spelling and writing, she will start talking about random and not relavent out of nowhere, extremely difficult time with tasks and task management (cannot use any aspect of a phone or computer anymore), and she has a difficult time comprehending conversations. She says she feels the words are in her head but they won't come out.

It has come to a point where I can barely have a functioning conversation with her. She told me she was driving the other day and forgot where she was and had to pull over. She has also been miserable - she complains about everything and she feels everything in this world is out to get her. She's turned into a completely different woman. Today she shared she's experiencing synesthesia where her feelings are associated with a color. She told me she places her dog in two dimensions in her mind (not exactly sure what this meant). This sounds like some type of hallucination?

She was tested by a neurologist and they diagnosed her with mild cognitive disorder. My father (who is a physician) and the rest of the friends and family feel it is Alzheimer's or aphasia. My mom claims it's because her husband left and she will get better once he is out. So far we have only seen her cognition and depression get worse in the last year and a half. There are some better days and some terrible days but it's mostly pretty bad. Does someone have any insight on what this could be?

My family is desperate to understand how this trauma could ignite dementia symptoms and if there is a possibility of her getting better or if we should plan for her to get worse quickly.