I agree that you have both behaved badly, but I have sympathy for both of you.
I think the period of maternity leave, particularly the first one, is a time that stresses most relationships and can start huge resentment building.
Most couples go from relatively similar lives - both going out to work full time but then both having free time to relax at the end of the day - to one of your lives changing completely (and both lives affected by the new baby).
From his perspective, he is going out to work hard and ‘needs’ to relax at the end of the day. That’s normal and what he’s always done. The problem is he doesn’t see or properly value what you are doing in the home, and views it as you having ‘time off’ whilst he’s working hard…and then he gets home and he’s been nagged about these jobs around the house. Maybe deep down he realises that he’s bitten off more than he can chew, and is overwhelmed, but too pig-headed to get someone in.
From your perspective, you have been stuck at home all day with the baby. What you do on maternity leave isn’t difficult stuff, but that’s the problem, it can turn into endless mindless drudgery. Then he comes home and doesn’t appreciate anything that you’ve done, thinks that you’ve been sitting on your arse, and then sits on his arse whilst you’re still doing stuff for the house AND you’ve got the night shift to do. On top of this, he gets to go out of the house, but you’re the one who has to look at all the shitty unfinished stuff and put up with the leaks.
This is before you start with any changes in dynamics about who is bringing what into the family and who has the most important role and who is the most tired.
It’s a tinderbox. We didn’t have the issue of all the diy around the house and my husband was helpful, but my God, sometimes I would seethe seeing him sitting there with his iPad moaning about how he had to ‘unwind after a busy day”. I had colleagues who returned much earlier than planned from mat leave because they just couldn’t be doing with this aspect of things.
If both of you want to fix things, then you’re going to need to sit down and talk. It’s tricky as there will be the tendency to go back down the road of defensiveness and anger about the DIY. However, you do need to talk about how you are going to keep the household and family life running now, as it is only going to get harder in the future. If you go back to work, then between you, you will need to manage two jobs, the household, the dog and a toddler/preschooler, and then the school run/homework/clubs. If you go back to work part-time, if you don’t get things straight now, you run the risk of being minimised because you are ‘only’ part-time and the resentment building further.
I don’t know if your relationship is too far gone. I do know that this stage of life is a flashpoint and that what is going on now is not acceptable for any of the three of you, so it has to either end, or change.