I really don't know how mothers in law are in your country, but in mine, once you get married, you get an enemy as a bonus.
There are a few people that can say that they love their in-laws. Luckily, I am one of those.
The sad part is that this hate is like a tradition here. I know also a couple of marriages that fail because of the parent. Sometimes, far away from them is not far away enough.
Usually, the man's mother is a manipulative bitch and she will treat the new member of the family the way she was treated when she got married, so is a weird circle of suffering.
Advice : Never live as a couple with the in-laws!!