MIL's behaviour irritating.!?!?!?TOO POSSESSIVE!!!!!

Hi,
A close friend of mine is suffering from MIL's torture.I need the help of ILs as well.She is married for 5 years and she has no kids. She has pursued the best studies required for mankind as it is her aim from childhood. Hers was an arranged marriage. Her family gave values to tradition,culture and goodwill rather than money. They were rich but they never boasted of their wealth. Her MIL is a divorcee(to be clear she has not given divorce officially-she has left her DH.) . My friend's DH is the only son to her and she brought him up and made him a good citizen(???). But the trouble started after marriage.She became over-possessive of her son and she started saying harsh words to her. Their marriage took place at a pilgrim place as per the groom's wish and sentiment and so my friend's family faced problems in planning the wedding. She pin-points that and curses her parents.She often compares herself with their family and makes her parents lesser. That hurts my friend a lot.She says "I can tolerate if she says anything to me but why should she insult my parents?What did they do?"
That MIL has three sisters but she does not maintain that much relationship with them.Just Hi Hi. But my friend and her family are a big family and they are very bonded to each other. Her MIL never allows her to go to her mom's place.She asks to wear dresses of her choice, food as per her choice etc. She does not allow them to have private life. They were not allowed to go to honeymoon also.Her son has not asked for dowry but they were told that the property will be distributed equally as per law.
Her DH is a dull idiot. He says his wife to simply tolerate his mother's irritation as she has brought him up with great difficulty facing this society as a single woman.He might be in a good position now but what has my friend to do with all the difficulties faced by her MIL? Why should she bear all this? After many ups and downs she is now pursuing a PG degree at a reputed university and this has still fired her MIL.She rejected it at first but after many explanations she accepted it. Now this friend of mine has a sister and and her marriage is on Nov.28. My friend's parents went to their place (which is very far from my friend's place) and invited them. But they r not coming to the marriage. She started irritating my friend that they did not carry out the proer rites while inviting to marriage and so on and so we r not coming.Frustrated, my friend said-OK.I m going.
Incidents like these are a part of her life and i don't understand why we ladies should bend down to those galling,irksome MILs how much higher studies we pursue . Is it our fate? Does all our life depend on the marriage and post-marriage life itself?Now what should my friend do ? Suggestions please......