So, as suggested earlier (and is always the case in this type of thread IMO) there is indeed more to this than just the monthly binge-drink:
. OP's partner says he's going out for a couple of hours, but it ends up being significantly longer, i.e. he's either lying up-front (he knows he'll be all night) or is habitually unrealistic regarding his own behaviour.
. If I suggest doing something as a family he can never be bothered the only time he does anything is when it's for himself. A much bigger issue IMO, rather selfish and sets himself apart from his family. His attitude problem is not just with regard to binge-drinking but extends to fatherhood in general.
. He gets drunk beyond belief and blows money that we can't afford to binge drink. So if they can't afford his binges,that means something else goes unpaid/unbought, presumably something for OP or DC.
. He knows it upsets OP but still does it, showing a lack of respect for her wishes/needs as he prioritises his own wishes/needs over hers.
.He's hungover all the next day and is snappy with OP/DC, so that they get to suffer from his hangover too.
Even if it is only once every 4-6 weeks, the fallout of his behaviour (tight for money, DC seeing him hungover/being snapped at, lack of trust and respect) is 24/7.