I have arranged to pop to my grandmas tomorow and said I would pick my mum up on the way and take her too. All fine.
Then today DS was slapped across the face with a ruler at school by a kid who just before easter pulled him off his chair banging his head on the floor.
I called my mum up tonight fuming saying DS had been injured again, she asked what had happened then as soon as I said I was going to see the teacher tomorow morning she went all sulky and said "oh, does that mean you're not picking me up like planned then??" and she was no longer interested in DS as soon as she realised it was impacting her. She's like this all the time. It's the same with illnesses, I called once to say I was really, really ill with stomach bug and before I could tell her the whole story she started going on about her own "slight cold".
When my sister was diagnosed with aspergers my mums first comment was "why me? why do I have a child with aspergers? how will this affect me?"
Its always the same. When my sister was getting really badly bullied at school my mum burst into tears one day and I felt for her until she said "this isn't fair on ME, I can't cope with all this" 
It bugs me. I know she probably doesn't mean to come across as being so selfish but it's so annoying.