Good plan OP.
Up your security.
Total silence going forward.
Thos SIL's that decided to get involved are no better.
This has been a gift.
You don't see it right now, but you will as the stories of the drama to come emerges, and it will.
Focus your time, energies and affections on those who wish you and your family well.
There is obviously simmering resentment in the family and it was only looking for an out.
How awful it came via a child.
So ugly and unkind.
But now you know.
Knowledge is power.
Whatever they say going forward, or your husband, they supported her, this awful behaviour, you being assaulted.
You need never have them on your property again.
Complete silence is the way to go.