Thank you very, very much for that detail and backstory. That helps me in trying to understand what you may be dealing with a little more clearly.
If your husband has been on medication before and is not, now, that in itself can be difficult both cognitively and emotionally. I have heard and read about depression and cognitive difficulties setting in after discontinuation of antidepressants.
I understand what you've said about the anger and even rages. Sounds like some stories in my family history, but 50 or even 30 years ago no one (at least no one in my family) was calling it depression. Now it is recognized that irritability and anger can be symptoms of depression.

I'll disclose here that a lot of mental health problems, both diagnosed and not, crowd my biological family tree-- both sides! I recognize that I've inherited a lot of tendencies to be easily 'unbalanced' but like your husband I have a distrust of the prescription drugs.
My approach is to be meticulous about my diet and supplements and other habits, on the theory that I need more of some things than other people. I have read that many of the nutrients we take in are necessary not only for physical health but also to make neurotransmitters.
There are a few things that I find absolutely essential for me to keep on a rather 'even keel'. This is not what will work for everyone, but through research and experience, I believe that these things help me. I am very much of the 'eat to live' philosophy. If I ate like most people I know, I would be a basket case in short order. (I also need to avoid stress. If I were a single parent, for example, or responsible for anyone else at all . . . that would be a disaster . . .luckily, I'm not.)
I don't know how your husband feels about taking a nutritional approach. If he is interested in hearing about it, this is what I do:
B complex capsule, not the whole thing, just open and tap out a small portion
biotin capsule, ditto, since the b complex has very little biotin in it
vitamin D, not every day, more often in winter months
magnesium capsule, dose out small portions throughout the day
soy lecithin granules, about 1 tsp, sprinkled on food (like oatmeal)
DHA supplement (I get one made from algae)
vitamin C capsule, small portions as above, may once/twice/day, with food
1/4 of a zinc pill at night
Is this a lot? Probably. Most people wouldn't stick with it. I have found I don't have a lot of choice, if I want to stay somewhat sane. But it doesn't really take any more time than putting on makeup.

I make it a priority to get the minimum 3 servings of veg and 2 of fruit per day. It helps that I really enjoy them, and that I'm fortunate enough to be able to aquire them!

I also track my diet, not every single day, but when I can, i try to log what I ate into either cronometer or into the 'recipe nutrition calculator' on myfooddata.com and check what I'm falling short on.

I try to move daily, even if it's just sweeping the kitchen or walking down the street and back. I'm currently trying to sit less. Easier said than done, in today's world!
This may seem like a weak band-aid given what you are dealing with. When I added some of the things above, it took well over a year to begin to feel the results. But I believe that I am less irritable now than I was at my worst. And like I said, what works for me may not work for your husband or anyone else.

You are so strong and so patient to have been dealing with this on your own for so long. I know how hard it is to want to help someone and feel like you are being shut out. That anger is hard to take, even when you know, logically, that it is not your fault!