You know, I remember people dogging me when my kids were little and pretty absorbed with their gameboy and such (even tho I usually yanked it from them during soical events), surprisingly enough they are now both IT specialists making 6 figure salaries. So to those moms that said my kids played video games too much----"WHATEVER!"
Unless there is more to the story than being revealed, it sounds like your SIL has other problems with you, jealousy, envy, etc. That comment you made over a year ago is not enough to warrant not speaking to you and shunning you for over a year.... good grief.
I don't think you should be mad at husband for this latest social event, it might be the tool to finally bridge this gap. You might say to husband "Well, you had a good time with Jack and Joe, do you see any signs that we might get back to being the normal family we once were yet?" Take this conversation and use it to your advantage by letting him know how hurt you still are that BIL and SIL are still not talking to you.
It's obvious your husband enjoys their company and they enjoy his, surely this is going to come to an end soon.
Does your son play video games yet? If so, you might use that as an opener to a conversation "Little Joey is taking after his cousin and is really good at __________ (name of game goes there); hopefully they both grow up to work for Apple some day!"
I can't help but think there is more to this tho, it can't just be from that one comment to make things go so awry.
I hope it ends soon, family togetherness is such an important thing, cousins shouldnt have to be suffering a non bond due to parental immaturities.