I'm sat in the bedroom alone and everyone else is downstairs enjoying themselves. I'm not too sure why I'm the one hiding away,
You don't know that they're enjoying themselves.
You're hiding because:
i) you're irritated;
ii) you're embarrassed that your (rational) argument hasn't persuaded the majority and the frustration was expressed emotionally;
iii) you were hoping that your relationship with your DH might mean that he's sensitive to the need that he might come and chat to you and give you a read on the situation with others?
hey’ll lie before they ever apologise, so there’s no point arguing. They’ll twist the story, change the way it happened and retell it so convincingly that they’ll believe their own nonsense.
You don’t need an apology to move on. You don’t need to surrender what feels right but it's unlikely to lead to anything productive to keep a dispute alive on Boxing Day. There’s just no point.
Some people need to be right more than they want to be happy. But it sounds like you would rather be having a good time with the others. Because, otherwise, it sounds like you go down tonight or you hope that staying alone means that you have a tricky conversation with your DH later (or none, if he doesn't come to bed until late) or have to breezily pretend nothing happened tomorrow morning. (And, nothing will be resolved anyway.)
Good Luck with whatever you choose to do.