It seems to be a common theme that the more you do for a family, the more exceptions you make for them, the worse they act out when something does not go their way.
The fact that the cord and scalding water was in reach of a child, at all, will work against you. There is no sugar coating that.
The mom acting out online is to be expected in this social media culture. As long as you don't play into it, it will fade quickly; drowned out by the rest of the noise online. Radio silence, consult your attorney ASAP.
I would prepare for medical bills and a possible civil settlement, though. The employee, herself, should as well. This could get pretty expensive. I wish I had better news.
I hope this is over quickly for you.