And, tragically, this situation is not uncommon. And get out of it is not so simple. Therefore, it makes more sense not to bring the situation to such passions, and try to solve the problem at the beginning of the conflict. Do not try to run away from problems. She - like a snowball - will only grow if it is not addressed.
your mother has a husband?
And, if it stands alone, the problem may worsen even more, because she has no personal life, and the whole meaning of life is the son and the house. Before you she was hostess, and everything was done by her and the way she wanted. Son was obedient and loving. And suddenly there is "this ... Believe me - the reason is not in you. So will any wife. And after the birth of his grandson the problem of jealousy can manifest itself in a different plane: in-law, which has generally not able to give birth to an unconscious attempt to take on the role of mother and take the initiative in raising the child.
Most conflicts occur because there is no clear idea of where to draw the line between the role of MOTHER
and the role of wife. . Mother-in-conflict, and not realizing that the married son is responsible for the welfare of his wife and children, but is not responsible for the welfare of the parent family. So to help parents must be proportionate to the younger generation capabilities and agreed in his own family. The phrase from the Bible (in today's society is not only men but women) "... Therefore a man leaves his father and mother and cleave to his wife: and they shall become one flesh ..." says the husband and wife are one flesh FAMILY that they themselves are jointly responsible for the quality of family life, for income and consumption for the upbringing of children.
I advice I can give to your wife:
let her mother-in-my mother calls
it should be praising her as a mistress, her culinary skills. If your mother a good cook let your wife take her recipes, or ask her to teach cooking, washing, ironing. grow flowers. your mom will love it.
and yet, let her make her nice gift. Your mom is important to feel needed, so let your wife asks her for help. This will make it a pleasant thy mother.
and the best thing is if your wife talk to your mom "heart to heart." This is a chance for them to communicate with each other to their own views on many important things.