Oooh, Katster, we've had exactly the same issues over here...
But before I forget (as I'm about to join in the DH bashing...) can I please raise something? All of our real names are in the facebook description which means they're visible to anyone. Not that I think anyone would be sad enough to come on here to snoop to find out what we're saying, but you never know... so basically, could someone in the moderator team hide the description? Sorry, I know I sound like a whinger, but I also know my SIL is on MN...
I've sort of accepted sucked it up (for now) as I couldn't be bothered with the constant rows, but; DH used up his leave (no pat-leave so only had 6 days annual leave to take) while we were in hospital. Despite us being in a private room and him being allowed there between 8AM-9PM daily, he only popped in for 3-4 hours each day, sometimes not even that. When he was there, he moaned about the heat/boredom/whatever. He's been in the spare room, and has (at my request) "helped" one night when I had mastitis. In our house, DH is the one who's been napping and sleeping for 8-10 hours... and yes, moaning about tiredness. In fairness, must say he's done virtually all the cooking, but still... he's out working in the day (like most DHs) and goes out biking/to do maintenance 2-3 nights of the week (and more than once has managed to time this with DSs temper tantrums at night) and either for a few hours on Sat and Sun OR more recently, all day Sat... This is despite having agreed while I was pregnant that he'd have to scale it down (ie live without his bloody precious bike) for a few weeks after the birth, as I'd find it hard going with no family around... but when it came down to it, he told me he needs fresh air and exercise and it's better for us that he gets it, and there's no way he can go without it even for a few weeks (or even ONE...) He'd changed one nappy in the first couple of weeks.
I spent the first few weeks feeling incredibly let down, disappointed and sad, as I'd imagined this cozy family life and a hands-on DH (who, I must quickly add, is not your traditional chauvinist who thinks there are women's jobs and men's jobs...) and suddenly I was all on my own. It got worse after my parents had visited, as I then had a taste of what it would be like if there was someone else around to share the worry and caring.
The reason I'm telling you this is a) you're not alone, and I'm very of those who have DHs who coo over the babies and do feeds/sit up in the night... but mostly because b) in some ways, it's got better.
Partly I believe what someone above said, that men just take longer to adjust. Partly I believe that my DH was somewhat traumatised after the labour and birth (we were left to our own devices, and I famously was "not in active labour" until they discovered the head coming out, so DH watched helplessly as I went through and unsupervised and unsupported labour with neither one of us having any idea of what was going on - with, I suppose, me having the advantage that I was most definitely NOT all with it, and just concentrated on breathing) but also, after one particularly bad argument (divorce was mentioned) he then confessed that he felt useless and didn't know what and when to do it or how to handle the baby... won't go in to details, but it left me feeling like me having a shower was inconveniencing him...
Anyway, now DS is older and a bit more "interactive" (aware of what's around him, "chatting" and smiling) DH seems to have pulled his socks up a bit.
So - I know it's infuriating. It's also really unfair and immature on their part, and frustrating and sad for you, but if you can muster the energy, take the high road and grin and bear it (and come here to went!) you may just find it gets easier.
If you've got a good relationship with your MIL/one of his friends who's had kids or someone like that, a stern talking to from them might do the trick...