Some of you ( i assume with no experience of these things ) are trying to make everything black and white . There are no simple solutions where the OP moves work location , the never sees GP again and everything is fine.
Child has complex needs and has positive relationship with GP.
Gp are not bad people , they are not abusers , regardless of what mistakes they made handling this incident.
GP struggle to understand and manage child ( as most people on this thread would ). They are presumably angry at SS who are telling them they cant be with their GC, when they are the ones supporting their DD and GS and not SS.
As PP have said, they are of a generation ( and I suspect culture ) where a slap in that situation is seen as not ideal but ok under the circumstances .
Also the GP must be devastated about the SA , they must be fighting the urge to go after the child’s father with a shotgun.
So “ no unsupervised contact “ has become YET ANOTHER task for the Op. she’s caught between her parents and her kids, having to impose a rule thats mostly about keeping SS paperwork looking good ( I'm assuming that the GP wouldn’t do it again now ).
It’s not helping her son and both he and her parents are angry at her. The one who is holding everything together here.
None of you pontificating on MN are going to watch her child for her while she mucks out the horses , are you ? None of you are going to pay her bills if she moves away ( from the animals and routine that her child loves ). It’s not that easy.