1. You did NOT stand at the alter, taking vows your Mother-In-Law. Therefore, when your Mother-In-Law gets out of line, do not delay to tell her to FUCK OFF!!! Stand up for yourself! Set your boundaries, now! Otherwise, you will only endure countless years of torture, stress, pain... And inevitably, a divorce.
2. Mother-In-Laws are bored and suffer from empty-nest syndrome. They hate surrendering "control" of their children, into adulthood. So, they use manipulation to keep a hold on their children. This creates tension in a marriage. (Usually severe.)
Key Words: Psycho. Senile. Manipulative. Dramatic. Sneaky. Delusional. Controlling. Interfering. Obsessive. Bored. Evil. Burden. Harassing. Game Playing. Meddling.
...Sooner than later (due to old age), until the reeper comes to take them back to hell.
Mother-In-Law from Hell Experience:
MY Mother-in-law is from the CAPITAL CITY of HELL!
I feel your pain!