"However, I have just been told that my husband and I are the only people NOT getting a gift to unwrap from her this Christmas."
"This has come from my husband who she told this afternoon. He said it was because she has already got gifts for the rest of the family. He didn't want to dicuss it much more."
That makes no sense. Or, does he mean she'd already bought those gifts some time ago but has since run out of money to buy presents for you? Still a bit unbelievable though.
And tough shit if he doesn't want to discuss it, he doesn't get to shut it down. I'd discuss it directly with her. along the lines of 'DH told me we are the only people you're not getting a Christmas present for. Has he got the wrong end of the stick, because I can't believe you'd single us out from the rest of the family like that.'
And frankly, if I didn't like her answer (the bought-the-others-already-before-this-crisis is the only scenario I can imagine finding acceptable) I'd be disinclined to have her under my roof. I'm sure those she feels close enough to to give gifts to will be more than happy to put her up, rather than leave her festering in a household she dislikes so much she pointedly excludes her hosts from her largesse.
Yes, I am being serious. Anything other than the scenario I suggested she is showing massive disrespect to you and your husband. Really, would a tin of biscuits be so hard for her to get? Plus telling her brother in advance, that's cold! I suspect she has form for batfuckery - you don't need this shit from her.