Weepy, reading your message, it could be me talking 7 years ago when our twin boys were babies. I used to get really angry when I read stuff like lack of partner support being one of the main causes of PND (which looking back I did have but didn't seek medical help with).
All I can say is it will get much, much easier fairly soon. Twins are a massive challenge. I remember being so angry and sleep deprived that I once tried to smash my own head against our bedroom wall! They are lovely boys now - still not without their challenges - but genuinely worth all the hellish times.
This is what saved my bacon in those early days -
going to so many mother/baby groups - anything local that was easy to get to - that I finally found a couple of lovely & likeminded women with similar aged children to hang out and have a laugh with (one used to bring cigs round to our house for me which I'd chuff madly on the balcony). Twin clubs can be good way of making contact although I didn't strike lucky with ours -found NCT group better.
The other thing was going back to work part time (2 days a week) when the boys were one which gave me a breather & some sanity so I could enjoy the boys more.
Have yo contacted twins and multiple birth association (TAMBA)? They have twin club lists and helpline, try website, sorry don't have link.
Things with my dh did improve very slowly, very glad we stuck together, tho the boys did test us to the very limit.
Good luck - things will get better xxxx