First, just want to say kudos to you for choosing to stick by his side. As someone who has struggled with depression, I can share that being abandoned is one of the most hurtful things we could go through. Although sometimes it may seem as if he is pushing you away and being "mean," it's clear that you recognize this is not the real him, but rather a way of lashing out because he is hurting. You seem like such an understanding and caring partner - exactly the kind of person he needs most in his life right now.
I would give him the space that he asks for. By sending you those articles, I'd say that he's working hard to explain how he's feeling, but oftentimes that's difficult, especially when the person we're trying to explain things hasn't been through the experience themselves. I think the absolute best thing you can do for him right now is to just be there, as counterproductive as that may seem. You are doing a very hard but good thing by letting him know you're sticking by his side during these difficult, emotionally challenging times. I understand your fear of losing him...that is completely understandable, especially because of the way he is acting. I would advise you to extend a kind or encouraging word every so often like you're doing, but don't overdo it. Give him time to think and stew a little bit. Maybe a text every day or two, but don't blow up his phone. He will know you are still there, even if you aren't always talking or together in person. By still being there after the storm dies down, you're showing him in the truest way possible that you are worthy of his trust and in it for the long run (I hope I'm right in saying that?). Over time, the two of you will learn how to navigate these choppy waters, and although it's never "easy," it does get more manageable.
Quick question, you mentioned his problem runs deeper than needing medication. Is he currently on medication? I'm wondering what else you feel would be a good means for working towards a healthier mindset...counseling, perhaps? Would he be open to that?
Blessings for taking the time invest in him.