To be annoyed with this mum

[wotnochocs]

To invite DD round for a sleepover and not mention that sibling has chickenpox.DD climbed in car with her friend and friend's younger sister.Just seen she has posted on FB 6 hours ago that sibling has chicken pox.
Sleepover is child's b/day treat, but my DD hasn't had it and has her own party arranged in 2 weeks, which is about the incubation period.
AIBU to think the mum should have mentioned it and let me the one to choose whether to expose DD or not.

ARGH!!!! YANBU! How unfair to not mention it or even continue to have the sleepover anyhow. I'm so tired of parents that don't mention their LO's illness'. We were just at a playdate and her and her two children had been very sick for a few days and the mum didn't say anything... now all the kids that were there are sick too. So infuriating. She does this a lot. She showed up to a play date once informing us that the reason they were late was because her DS was throwing up... all the kids got the stomach flu the following days.