I agree, she's either sussing your house to see who's there or she's walking back and forth in the hopes that you won't be able to resist coming out and picking up where she left off (sans vomit). Good luck with that one, WORKzilla dearie! Bonkers!
As far as the school gates go I think it's a case of 'them that know don't care, them that care don't know'. People will believe what they choose to believe regardless of the facts of the matter and in the long run if you lose someone because of her lies, then that person wasn't a friend to begin with.
But perhaps you'll want to wear a 'sandwich board' on your first day back saying on the front "No I never agreed to provide summer childcare for WORKzilla" and on the back "Not my circus, not my monkeys". Or maybe just 'WORKzilla's nuts. No ifs, ands, or buts'.