Ok lets be honest here. This is about your feelings not your daughters.
If you?re asking AIBU to be annoyed my husband gets to go off on a fun weekend away when I?m going to be solely responsible for a bunch of 9 year olds overnight then the answer is no. If you then tried to stop him going for no other reason than ?well, he could put the other dcs to bed, I suppose? then the answer is yes (IMO).
If you don?t get to go away with friends and this is about you putting family before 1st, 2nd and 3rd and feeling like he doesn?t then maybe you need to re-evaluate your friend?s, family, personal time balance.
Personally I wouldn?t be reinforcing with your daughter that it?s ok to expect a multi-day festival of fun every birthday, an ex friends parents did this and she actually insisted that I take a day off work to celebrate her birthday. Not the reason we aren?t friends but symptomatic of her selfish behaviour. Sometimes even parents can?t be there to celebrate birthdays, it?s not a milestone one and hopefully this stag do is a once in a life time event where as your daughters birthday isn?t. Especially when she?ll be wanting as little interaction with her ?embarrassing? parents as much as possible.
And JenaiMarrHePlaysGuitar really? Surely it?s the responsibility of the parent to decide if they make the date not the organiser to work around an 8 / 9 year old. And what if that was the only date everyone else could do? In this case the husband said the weekend would be ?awkward? therefore doable but tricky, other people said it was the only weekend they could do. Therefore stag went with the majority, that isn?t unreasonable (godfather or not) if you try and please everyone you get nowhere.
However on the basis that the husband is starting to sound like a selfish twunt I think the issue isn?t about DD?s birthday and the stag its about the relationship and feeling like you matter to him. In his defence on the missing the birth (which I?d be mightily annoyed) people always say ?oh they?ll never arrive on time so he probably thought 11 days before due date was safe enough. However why didn?t you put your foot down and say I?m not happy about you going away in the few weeks leading up to the birth? If you did and he ignore you then you really have bigger fish to fry than a sleepover.