Bk of course not. If you were depressed and down you would want to know that your partner of 35 years has got your back. I would!
At the same time, have you communicated with her that if you are in therapy and she is not, the likelihood of you growing apart is quite high?Therapy changes us, we become new people through doing the healing work, and if she is not willing to change with you then indeed she is lining up hard times for herself. I mean even if you were technically still married you would not be together in values and outlook. That is why often our partners are threatened when we start to grow and change. Maybe if you could find a quiet moment where she is open to communication this would be something to raise in a very non-threatening way?
When my uBPDgf goes on a rant I do try to listen quite carefully. Important things often come out during dysregulation, things she is too scared/nervous to talk about otherwise (maybe for fear of rejection?). One does have to listen quite carefully because of course it gets communicated through a BPD lens. Over time I have learnt to ask her: what is it really? What is bothering you? What is the cause of this anxiety? Often just the question is enough to stop a rage and get her talking normally. Weird way of communicating I know but communication at any price I say.
At the same time I tell myself this is not about me. Yes, we get projected upon and when she rages it is "khib this and khib that". But as I tell myself this is not about me and try and get deeper into it often it turns out to be something quite specific which has caused the dysregulation and we can get to the root of it and change the cause. Sometimes it is indeed about me - I am not perfect and very much not so lately - and then I can validate quite justly which pleases her no end. I can think of at least once (probably many occasions) where I saved the relationship simply by saying with sincerity "yes, you are right, I was an a--hole in that situation. I am sorry!". Whether it was the first time her life anybody had validated I don't know but it turned things right around. Of course it is a given that this has to be done without FOG, one can only validate what is true.
A stance of deep listening while not attaching to ego is really hard and so I practice it a lot in meditation and prayer. With a firm belief in miracles
It would help the depression at least if she could be tempted out with you for walks, maybe join you in prayer? Don't phrase it as "do this for your illness" but simply as in "I would like your company", "I need you to be with me in this". Remind her that she is loved and intimacy will follow.
Good luck , you are doing great getting into therapy and support group, I am sure with time you will have a handle on this life crisis.