I don't know what to say to you, except give you and your H a virtual hug.
His family are behaving appallingly. No-one wants to discover there's been abuse in the family but their shock/embarrassment/awkwardness/disgust or whatever is nothing compared to what H went through as a kid.
Quite what your alleged "stuck-up-ness" has to do with something that happened to him as a child and/or his brave decision to speak about it now I don't know. You could be the snobbiest woman in the world and it should have nothing to do with how H's family behave towards him over something like this.
I wouldn't condone them not wanting to speak about it, neither would I condone them burying their heads in the sand about it ..... though I understand this is quite a common response from close friends and relatives unable to come to terms with it themselves. However, on top of that, to snub him, not include him in fanily events and to make snide, insensitive remarks ..... well, that's downright nasty.
I can't begin to imagine what's making them behave like that. Even if they refused and/or didn't want to speak to H about "it", you'd have thought that if they cared for him they would be doing all they could to reassure him that his brave stance over the abuse has done nothing to alter their feelings for him.
Do you think there's any possibility that any of the family actually knew what was going on ? ... could that be why they're behaving like this now, because they felt guilty at doing nothing about it ?
It's easy for me to say I know but he really is better off without the lot of them - particularly his father. But I completely understand it's not so simple for H and he must feel heartbroken. And in your shoes, I would be beyond fury if my partner was being treated like this.
Does H, or you, feel able to directly challenge the family about the lack of support / snide remarks / snubs and so on ? I'm afraid I wouldn't be able to hold back and would take the risk that a rift would be created. After all, the alternative, of being "punished" would, to my mind, be pretty much a rift anyway.
Is there anyone in his family who's been sympathetic and may be able to throw some light on the others' reaction ..... though God knows, I'd be hard pressed to think of a justifiable excuse for this.
And anyone who continued to socialise with my abuser ...... well ..... that says it all. What excuse can there be for that ? Either H's dad thinks he's (H) a liar, or else he doesn't care. Poor H, they sound like a horrid family.