Your husband could be grumpy but he is still and adult and he is able to behave like a decent human being being, right?
Kids may not be as ok as you think, words hurt and they may be internalize them.
Your gc are seeing his grandfather for whom he really is and is not a pretty picture.
I would tell my husband to behave like a decent human being or stay home
The King's Speech To Announce 'All But The End Of Leasehold System' System'


