Bit of background:
Not the best relationship with my Mother for some years now. There are various valid reasons for this which I won´t go into.
She has recently been diagnosed with early stage Alzheimers so of course is very down about it. However she has always been very judgemental, negative and critical of others, a negative person on the whole.
Anyway
She is visiting at the moment out here for a few weeks. (we don´t live in the same country) This happens quite regularly and I admit it drives me mad as its all too intense.
DS1 4 has been ill this week which admittedly has meant he has been somewhat more grumpy than usual. Yesterday my Mother asked him to do something to which he replied with a shouty typical 4 year old "Nooo"
Her retort was "You´re horrible" right to his face
When he was upset later in the evening she called him "a big girl´s blouse" 
I decided to speak to her about it and with hindsight I know I shouldn´t because she did just what I thought she would. Turn it back on me saying I am being "ridiculous" and "sensitive" That she was "having a laugh" it was "just banter"
WTF??? Banter with a recently turned 4 year old????
Surely my reaction of outrage is normal?