I know that it is within your power to make her stop doing (7) and the cupcake part of (8) for sure. You direct who is allowed to pick up your son from school, eat lunches with him, etc. You just need to notify the administration and have a note placed in his file in the office.

You probably can also stop her from doing (1) and (2).

I am not sure it is (yet) time to go all out, but...

Given that she took step (6), I think it is time for you to act at least in SOME fashion.