To what extent can the husband’s relatives interfere in his wife’s life?
Question

What are the rights of the in-laws (the husband’s brothers and sisters) in Islam? Do the father- and mother-in-law have the right of obedience? Do they have the right to enter my room with or without permission? To what extent should I obey them with regard to my clothing, cooking, childcare, keeping house and going out of the house? Do they have the right to interfere in our marital life? Do they have any rights with regard to our work, where we live, education and the like? Do I have to ask their permission to visit my family? Do they have the right to know all the details about our life? Do I have to obey them and shake hands with my husband’s relatives? Do my husband and I have to attend weddings in which there are haraam things?.
Praise be to Allah.The wife does not have to obey anyone among her in-laws, whether that is her husband’s father, mother, brothers or sisters, in any matter, major or minor, unless they tell her to do something which is obligatory according to Islam, or forbid her to do something that is haraam. In such matters she has to obey, whether that comes from a relative or a stranger, an in-law or anyone else. 
With regard to the husband, she must obey him in matters that are right and proper, because Allah says (interpretation of the meaning): 
“Men are the protectors and maintainers of women, because Allah has made one of them to excel the other, and because they spend (to support them) from their means…”
[al-Nisa’ 4:34]
Ibn Katheer (may Allah have mercy on him) said, discussing some of the husband’s rights over his wife: 
Allah has given the husband rights and commanded the wife to obey him; He has forbidden her to disobey him because of the fact that he excels her and maintains her. Tafseer Ibn Katheer, 1/493 
It is not permissible for any of your in-laws to enter your room without your permission, because Allah says (interpretation of the meaning): 
“O you who believe! Enter not houses other than your own, until you have asked permission and greeted those in them; that is better for you, in order that you may remember”
[al-Noor 24:27]
If any of them enters your room with your permission but he is not one of your mahrams – such as your husband’s brother – then there has to be one of your mahrams present, so that there will be no haraam khulwah between you (i.e., being alone together). You must also observe full shar’i hijab, and be certain that there is no risk of falling into fitnah (temptation). 
Despite all these conditions, it is still better for him not to enter upon you in your room; this is purer for the heart and farthest removed from suspicion. Allah says (interpretation of the meaning): 
“And when you ask (his wives) for anything you want, ask them from behind a screen, that is purer for your hearts and for their hearts”
[al-Ahzaab 33:53]
And the Prophet (peace and blessings of Allah be upon him) said: “Beware of entering upon women.” A man from among the Ansaar said, “What about the in-law, O Messenger of Allah?” He said, “The in-law is death.” 
Narrated by al-Bukhaari, 5232; Muslim, 2172. 
Al-Nawawi (may Allah have mercy on him) said: 
With regard to the Prophet’s words “The in-law is death,” what this means is that there is more fear with regard to him than anyone else, and evil is to be expected of him, and the fitnah (temptation) is greater because he is able to reach the woman and be alone with her without anyone denouncing that, unlike the case of one who is a stranger. What is meant by “in-law” (hamu) here is the relatives of the husband apart from his father/grandfather and sons/grandsons. Fathers/grandfathers and sons/grandsons are mahrams for his wife and it is permissible for them to be alone with her. The word “death” here does not refer to them. Rather what is meant is the brother, brother’s son, paternal uncle, cousin, etc, who are not mahrams. People are usually careless about this matter and a man may let his wife be alone with his brother. This is what is referred to by “death” and should be prevented more than her being alone with a stranger for the reasons mentioned above.  
They do not have the right to force you to do any of the things you mention, such as how to cook, how to dress or other things such as working and teaching etc, unless that is by way of advice and kind treatment, not by way of compulsion. 
It is not permissible for them to interfere in your and your husband’s private affairs, but if they convince your husband not to go out on trips and he tells you to stay in the house, then obey your husband, and be patient and seek reward. 
You do not have to ask permission from any of them to visit your family; that is not their right. You have to ask your husband’s permission, and if he gives you permission then you do not have to ask permission from any of them. 
They do not have the right to know the details of your life (you and your husband), and it is not permissible for your husband to tell them of any private or intimate matters between the two of you. 
Your husband has to honour his parents, and you should help him in that. You should not be the cause of a split between him and them. You will see the consequences of that in your children in sha Allah. 
Your husband’s visits to his parents should be on the basis of need. Something may happen to his parents which requires their son to visit them a great deal, such as sickness and the like. You husband has to pay attention to that. 
With regard to your serving them and doing housework, you are not obliged to do that, but if you do it as an act of kindness towards them, or to please your husband, that will be good and you will have the reward for that in sha Allah.  This is something that will raise your status in the eyes of your husband and his family in this world, and will raise you in status in the Hereafter too, in sha Allah. 
With regard to your living separately, your husband has to ensure that you have a place where you can live separately, but there is nothing wrong with his parents living in the same place with you if the house is big enough, and if that will not cause you any harm.
With regard to your life being under scrutiny, his parents have no right to dominate your life. Try to communicate in a proper manner with your husband and reach an understanding. If he can resolve the matter, all well and good, otherwise there is nothing wrong with you speaking to his family in a wise and mature manner. If they do not respond and the situation continues as it is, then be patient and seek reward from Allah. 
With regard to your shaking hands with men who are not your mahrams, this is haraam. There is no obedience to any created being if it involves disobedience towards the Creator. For more information on the ruling on shaking hands with a non-mahram, see question no. 21183. 
It is not permissible for your husband to go to wedding parties in which there is noise and sin. For more information see question no.  10957. 
Finally… 
Our advice to husbands is that they should honour their parents with regard to that which is right and proper, but they should not obey them if they transgress the limits set by Allah, or help them in wrongdoing, which includes mistreating their sons’ wives. They should discuss with them in a way that is better and not prevent them from obeying Allah. They should be strong in adhering to the truth and confront those who stand in the way of their implementing the laws of Allah in their homes, because the Muslim does not acknowledge any authority over him except the Qur’aan and Sunnah. They should also beware of those who call them to commit sin. 
If the husband thinks that the interests of sharee’ah dictate that he should keep his wife and his family apart, then there is nothing wrong with him doing that. 
We should be tolerant and be patient with one another, and we should not forget to be kind to one another. We should speak to one another in kindness and be patient,  and ward off evil with that which is better. We should speak well to the slaves of Allah until we meet Allah. 
Allah is the One Whom we ask to set all our affairs straight. May Allah send blessings upon our Prophet Muhammad.