"His excuse was ‘I didn’t think you cared’. Well, turns out I do."
Yeah. I bet it is a downer to come home from a blissful two weeks away to a full on toddler, BF baby, sick dog, sick wife scenario.
It's even more of a downer to have been coping in that scenario on your own and then have to put up with the returning hero's strop and pathetic excuse for not giving you any kind attention.
So he made a decision that you didn't care about such as silly commercial holidays such as Mother's Day, thereby deciding that he's absolved from any effort. The sillier and more artificial a holiday it is, the easier is to paint you as silly for caring about it.
He still thinks its about Mothers Day.The reason mums get mad about this holiday when its overlooked is that it's hardly a big stretch to take the time to acknowledge with they do for the family... which is not about spending money but about acknowledgement and teaching the children to acknowledge it too, is a good example to them. It's an acknowledgement of your constant care and effort. That is not silly.
Turns out he was wrong, but instead of saying Sorry I was wrong and I will make amends, he's taking it out on you, how very dare you call him out on this? Sulky, Snappy, expecting YOU to apologise for enlightening him.
But It's not about Mother's Day
It's about the fact that you made it possible for him to go on a relaxing two week break, whilst you too care of the children inc small BF baby and sick dog alone, you had to watch him distributing presents and realise - nothing for you. You've had a hard two weeks and he's doesn't see any reason to have any empathy about that. He in turn was mad that he didn't get a fawning welcome, but he didn't give you a fond welcome. There's no give and take here. In that one partner is doing all the effort and giving and one partner is doing all the taking and throwing a strop if this is even mentioned as its spoiled their vibe.
People who are returning sulking and snapping and not doing anything to make up for the absence or showing any gratitude to the person who made it possible do not deserve an apology from the person they've been mean to.
They need to be told calmly and clearly why this is not acceptable and let it sink in, so they have a chance to make amends, or at least to try to work out what that is or even (bare minimum) understand why the behaviour is unacceptable.