My Grandson is 3 and my d-i-l will not let him come to my house for the weekend anymore. She says we are 'brainwashing' him to hate her.
Not really, but I suggest that you contact a local attorney and contact them about this. They will be in a better position to help you when they know all the facts.
If you want to see your grandson, be nice to your daughter-in-law. She controls the access to your grandson.
My nephew is no longer with his girl friend. We treat the mother of my great-nephew like a queen. We get to see him all the time. Why? Because she controls the access to the kid.
If you "piss" her off, you won't see the kid.
You are a female and you should understand how a female thinks!