Welcome Pagan: I'm sorry about your situation with your wife. Sounds like her behavior has a negative impact on you. It must be tough to deal with your wife's issues, while trying to manage your own anxiety and depression.
My wife has ME/CFS and other medical issues making her housebound. I think my she may have BPD, as she regularly splits, with regard to her family members. She suffered childhood mental and physical abuse, physical abuse and rape in a previous relationship and has a history of depression, drug use and misuse, violent mood swings and impulsivity.
Were her parent ever diagnosed with a mental disorder (personality disorder or something else)?
Has your wife ever received treatment for depression (meds and/or therapy)? I believe ME/CFS has some symptoms similar to depression?
I work and suffer from anxiety / depression
Did your anxiety and depression exist before you met your wife? Perhaps you had it to some degree, but it has been exasperated by your wife's behavior? Are you receiving therapy and/or meds to help you?  :)o you have some healthy ways to self-soothe and try to relieve your anxiety and depression (exercise, meditation, mindfulness, music, books, etc.)?
There are several links to helpful information in the margin to your right. Within the section,
"What is the first step? - Basic Tools, you will find a link to Setting Boundaries and another link to Ending Conflict. These tools might be a good place to start learning some skills or to fine tune some skills you already have. Mastering some communication skills/strategies, along with setting boundaries, can make things easier for you.
Do you think it might help your wife with her need to vent, if she got connected to a message board for those suffering from BPD or other forms of mental illness/personality disorders? Since she is housebound, it may give you some relief, if she had another avenue for venting?