"and family", which is a pretty normal thing to see on cards.
I know it's ordinary to see it, but I don't think it has an official sanction, and I personally think it's not polite. I'm tempted to do it, because I get lazy, but I don't think it's warm at all. On the envelope, yes, it's OK there.
But I don't consider it good form in the salutation.
(and if it's just one other person, "and family" is probably not that much less work than "and Sharon" or something. Oh, I suppose f-a-m-i-l-y is fewer letters than J-e-n-n-i-f-e-r, but only by two.)
It's not so much a deliberate insult as it is an offense of omission--you left my name out, which means you didn't think it was important to "speak" directly to me. I'm an afterthought--a pretty "after" afterthought, because you didn't even bother to write my name. So, yes, that's insulting, but it's a passive insult, not an active one.
I don't personally get upset about it, but I wouldn't ever label it "good form."