You don't want to appear petulant or passive-aggressive. You also want to always do The Right Thing. The Christmas decorations are at LEAST half hers.
Give them all (or 1/2, if you're wanting to use some) to your intermediary, and ask him -- if your wife should inquire -- to tell her that he has had them since the day after she e-mailed (texted?) you asking for them, and he was just waiting for her to contact him.
End of "caving in" objection; SHE looks like the idiot for not going thru IM in the first place.
