Relocating and the stress of rebuilding the business from the ground up is always so hard. I have done it four times, myself and struggled too. That alone would be enough stress to lose sleep but to compound that with a difficult client is a lot to deal with. I am glad you let them go, life is too short for that.
Most termed parents lash out at being told no and file false complaints and online bad press. There is no cost to it for them, that they are aware of.
They forget we generally know each other and talk pretty regularly.
Her bad attitude will come back to her in her life, don't you worry about that one little bit.