@pakman,
I'm failing to see the problem here.
Your inlaws are saying not to visit them. They are nasty to you in all sorts of ways.
So don't visit them. Does that make you a bad daughter-in-law? Absolutely not.
Go visit your mother and get your work done and have a lovely time, and don't give your inlaws a second thought. Will they gossip and complain about you? Count on it. But here's a secret - they will do it no matter what you do. There is just no pleasing some people, so don't even try.
Have a wonderful time with your mother.