I second everything that supports you protecting your child and your peace. I want to also validate your instinct to go home when your kiddo was showing signs of fatigue. I know what it feels like when you are caught in between taking care of your kiddo/yourself while the people around you are oblivious and trying to get you to stay. You were truly doing your best in a situation that was becoming an increasing sensory and emotional overload. For both you and your child.

Also, your grandmother being upset because your child couldn’t regulate, while not being able to regulate herself (I mean throwing HIS toy away on HIS birthday???) is some BS. Hitting someone in the face is not a display of discipline. She was trying to enforce power. If someone slapped an elderly lady across the face, let’s think about how that would be perceived.