My MIL called me this evening when I was making tea - who does that to a working mother? So I was already grrr. She then demanded that she had my 2yo dd overnight tomorrow (Friday) as she hasn't seen her for ages. I said no, but actually Saturday would be convenient as older dd having sleepover Sat and bday party on Sun. She said it wasn't convenient as she had plans (to go car booty shopping) on Sunday very early.
I stood my ground despite her trying to guilt me into it as I have been working my arse off all week and have barely seen the wee one and will be tied up with party shenanigans (DD1 will be 13) for Sat eve and lots of Sun (cinema then out for tea). She hung up on me
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I often give into her and find her difficult to manage and she drives my dp completely fucking mad too. He, by the way lost his job a few weeks ago and she knows how hard I am working to make ends meet so should know how much weekends mean - she doesn't offer at times that would actually help. Him too - he has taken a really shitty fast food delivery job and is pretty down 
AIBU to not bother phoning her to clear the air (I hate an atmosphere) and just to let her come crawling back to me...?