You know, that first night of entirely broken sleep can come as a huge shock to the system,and it’s sometimes understandable that people take a little while to get into a pattern and where emotions run high. So I can e.g. see how you might have fallen into a cycle of his wanting a full night’s sleep and realising how hard that was when he first went back to work and your DD was first home, thus culminating in a place where you ended up in the spare room.
But your DD is ten weeks old now, and this is the weekend, and it appears that what has happened here is that he’s gone from feeling entitled to unbroken sleep on work nights to feeling entitled to unbroken sleep every night. And it’s not on.
So i would be taking back control now and telling him that you’ve done your stint in the spare room and that while he’s welcome to stay in the main room, if he doesn’t like the broken sleep he will be the one to move out into the cold room.
I would also tell him that on weekends it is you who gets the lie in, and not him.
I do actually understand how easy it can be to fall into the pattern of doing all the overnights. I did as my eXH commuted for work and had to be up early. Plus I was home, and if I’m honest, I always felt as if I should be the one to be there for DS, iyswim.
But the difference is that my eXH absolutely would have done the night feeds if it had come to that. And I had a fairly good sleeper so on the whole it wasn’t a major major issue for us.
But eXH did used to take DS out to the shops etc at weekends to give me a break, and if he was ill we both used to get up and see to him - ex would e.g.clear up and I would be with DS but we still were both up.
I can even see how a partner might struggle with the broken sleep, especially in the beginning. But anyone who actively takes steps to make themselves the priority and has expectations of their partner who is the one going through the broken sleep to make them priority as well is a selfish bastard.
Tell him you already have one child, your DD, his position as baby of the family has now been filled by an actual baby, so time for him to grow up.