OP when I first read your post, I thought how much you sounded like my wonderful DH.
apoligies but I only got as far as page 5 and am at some of the comments you have had! But I suppose you wanted a female perspective
He is not even in AIBU for farks sake!
I dont have first hand experience with PND but I do remember those feelings of wanting too be the one in full control but at the same time feeling completly out of my depth. And that as his Mother I was the only one who could understand this little person and meet his needs appropriately. (I have 2 boys, 21/2 & 8 months)
The broken sleep is hard - hence DH going to bed at 8.30 tonight & me MN'ing (DS2 8 months & still not sleeping through grrr) so I understand your concerns about your wife.
I also remember "losing myself" with ds1 , I was no longer "me" I seemed to be either DS Mummy or DH wife, not just me. It helped when I went back to work & also going out for few girly nights and visiting some child-free friends from Uni for a few hours. But it was also hard for me at first to actually go out for longer than an hour & actually trust DH (or my Mum) to be able to take care of DS, and so therefore relax enough to enjoy myself. I also BF both boys & felt it was my duty to always be there for them to feed them, I always felt guilty leaving them with a bottle - totally unreasonable I know!
DH is bloody brilliant but he still gets a hard time from me & I dont even mean it half the time, it just comes out my mouth without me thinking first.
So you put those factors together with PND and any relationship is going to struggle.
Also DS1 has always been a "Daddie's boy" they have had a very close bond from an early age. DS1 only ever wanted Mummy when ill, and this has been from a few months old, so I totally disagree with the others that say that people can just come & go in a baby's life at that age.
These things take time, just try to remember your wife is ill and these things are symptoms of her illness.