Yesterday I talked about the problems in-laws can cause a couple, focused on when it’s his family. Today her family.
This is more difficult for a couple of reasons – first and foremost being I am talking to you, not her. Second, unhealthy, clingy relationships are far more common between mother and daughter than between a son and either parent. Finally, hostility is usually less open when it is her family, and especially her mom. That is not to say it’s less harmful, just more difficult to pin down.
The solution is the same as what I suggested yesterday – she needs to draw a clear line and stick to it. The problems are getting her to see the need, and to see where the line should be. My suggestion would be to talk about how it is hurting your marriage, not about how it offends or hurts you. Because she is relational, telling her something is hurting your relationship with her is going to get more attention than making it about you.
One warning (and this applies to your family as well) – if you are frequently using the grandparents as free babysitting, you limit what you can do. You need to be willing to give up the babysitting perk if cutting back contact is the only way to deal with the problem.