I suspect your DH may have narcissistic tendencies, and has persuaded everyone around him that it's 'depression', when actually it's much more complex than that.
I am very concerned about you, actually, more than any other MN I've read about on here recently. You sound like you're doing brilliantly in a bloody tricky situation, but why are you so prepared to put up with all of this? I don't know anyone that should put up with this behaviour from their partner, depression or not.
Was he really always the wonderful person you say he was until 2 years ago? In his thread hijack even he says he spent years and years hiding his true feelings.
I don't doubt he loves you and wants to fix things, but as you say, it's actions not words that count. Love is an action, it's what you do, it's not just something you say to get away with shitty behaviour.
(I speak from exhausting experience. I love my exDH very much still, but I had to get away from him. He manipulated everyone and me to the point where I was suicidal. He trashed my life and my brain, and still plays incredibly clever and complex mind games with us all.)
In my opinion, his posting on here and his behaviour is classic Narc territory. His boundaries are VERY blurred if he feels he can crash your thread.
The complexity of the situation you're now in is typical of the chaos they cause. A relationship really shouldn't be this complex and it definitely should not revolve around one person so much. Hope you get a chance to get to the bottom of all of this.