night weaning won't necessarily help. You may find that he still wakes at night but you have no way of quickly sending him back off to sleep!
with regards PND, if you stop breastfeeding and you really don't want to you'll end up feeling guilty, which may actually exacerbate how you are feeling rather than making it go away.
i think other posters are spot on when they say that the issues are separate but are getting confused. I think it happens a lot and people often blame breastfeeding, but imagine if you took breastfeeding out of the equation and the problems still remained. all you'd end up with is no quick way of settling the baby!
if I were you I'd see the GP or Healht Visitor about possibility of PND.
I would see if your husband is willing to try and settle baby for at least part of the night, even if you bring him in with you at some point. Perhaps you could try and cut down some of the night wakings even if you don't stop them completely? although as I said before, even if he doesn't feed at night that doesn't necessarily mean he won't still wake, but there is no harm trying if you think it'll help.
I think it's important that your DH sees that this isn't a breastfeeding issue and it isn't something you can solve yourself... he needs to help
I would also look at how you and DH can share a bed. perhaps that means taking the side off the cot and pushing it up against your bed so ds can sleep in there and still be with you?
then, i would organise a night out! or if not a night out then an evening with a film and a nice dinner and no TV and just try and reconnect a bit