[quote ChargingBuck]I feel I was wrong at shouting, but I felt really violated and needed to stand up for myself. I went through all the alternative options first (DH having a word, etc).
Hey - stop beating yourself up.
Losing your cool ONCE is hardly equivalent to being persistently mocked over several years.
Most of us do similar - we bottle up frustration, resentment & rage because we don't know how to express it or fear confrontation or the inevitable backlash from the person who's been needling us. Then it boils over ...
It happens because many of us lack assertiveness skills, so yo-yo between putting up with crap & the occasional volcanic eruption.
Start fixing that with this lovely book - ]]
She then left without having dinner, after DH also said she was out of order. 
Sorry Eurydice, this made me laugh because I hoped so hard she stomped home hungry & sat herself on her own naughty step.
She had it coming, so forgive yourself & move on.
You tried very hard to advise, warn, explain, & even get her own son to have a word & she rode rough-shod over all of it.
You know it's not about your accent or anything, don't you?
It's about power.
MiL continuing to take the piss despite your obvious discomfort & requests to stop it was a dominance display.
As to the 'moving on' bit - don't expect this incident to have 'cured' the problem.
Because the problem isn't her racism & piss-taking.
The problem is her view of herself as your superior, & her acting out power-plays to ensure you feel it.
So be prepared for quite a lot of:
- passive aggressive sniping worded to cause you grief without quite being 'challengeable'
- wounded martyr act
- fake illness act / "oh my nerves" act
- direct blame eg Eurydice has Hurt My Feelings She Must Apologise
- more power play, eg sneaky manipulations like letting you down last minute on the childcare day
You can handle it - more tools for your kit in links below.
And I would look into alternative childcare arrangements - not urgently, not dramatically, but to give yourself a back-up plan, & to ensure that you know you have it covered.
You don't want to be dependent on this woman's goodwill.
That way, you can't be emotionally blackmailed into putting up with any of the above by way of her guilting you about childcare, or threatening to withdraw it if (I can imagine her saying this, so am sure you can) "Eurydice can't behave herself."
Well done for losing your rag btw.
This was a boil that needed lancing :) xx
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outofthefog.website/what-not-to-do-1/2015/12/3/jade-dont-justify-argue-defend-explain[/quote]
Thank you so much @ChargingBuck, such useful resources! I will make sure to read/go through them.