I can see why the OP feels hard done by, tbh - she's said that she feels like an "add-on" in her mother's life, and so she clearly wants to please her, make her mother take an interest, like her more - and her DH didn't facilitate this by falling over himself to accommodate the selfish flaky woman who turned up late on Christmas Eve and expected everyone to change everything for her.
OP's MIL made some effort to accommodate said flaky selfish woman - but flaky selfish woman decided that it wasn't going to work and refused. DH quite possibly got the hump about this and then dug his own heels in.
OP is caught in the middle - she doesn't want to upset her DH, but she wants to play the adoring daughter to flaky selfish mother - and so she has to make a choice. Now she's still pissed off at being forced into making that choice, and thinking she made the wrong one (possibly from later input by selfish flaky mother) and is feeling hard done by by the lot of them.
I think, if the OP has had a lifetime of playing catch up to be noticed/liked/important to her mother, then it's going to be hard for her to suddenly be able to go "you know what, fuck this, you don't get to turn up so late on Christmas Eve and disrupt everything, and expect everyone to be thrilled that you're doing just that. You just don't get to do that. So we'll carry on with our plans, and we'll see you back here on Boxing Day" - and surprise surprise (not), she didn't manage to do that.
So I think she has some reason to feel aggrieved - but the solution is in her hands only - take control, decide what SHE wants to do and do it.