His family have cut him off because he got married without their approval
Question

                I am a young man, thirty years old. I wanted to get married to a girl whom I love and she is religiously-committed and of good character, but my mother and sisters objected to me marrying her for several reasons (including the fact that they wanted me to marry someone from a higher-class and wealthier family). I tried to convince them but I did not succeed. They threatened to cut me off if I went ahead and married her, but I did not pay attention to their threat. I went ahead and married her, and my family have carried out their threat and cut me off completely.
, I am happy with my wife but I feel very sad about my family’s attitude and their letting me down treatment at the time when I needed them to stand by my side. I have tried to reconcile with them after my marriage and I have asked some good people to mediate, but without success. Now after nearly a year I feel that we are very far apart and that the rift between us is even deeper. Am I committing sin in my attitude, and does my mother have the right to use her right that I should honour her as a means to force me to do what she wants and and take away my right to decide my future and to choose my life partner? May Allaah reward you with good.
Praise be to Allah.Our advice to parents and siblings is not to 
    prevent sons from getting married to whomever they want, if she is religiously-committed and of good character. 
They should strive to make their sons happy; 
    marrying a son to a woman he does not like puts him in a difficult situation: either he will divorce her or he will live with her even though he 
    does not like her and his heart is attached to another. This is harmful for him and for her, and exposes the family to disintegration. 
The parents do not have the right to force 
    their son to marry someone whom he does not like, and it is not permissible for them to cut him off if he goes against them in that. It is haraam 
    for a believer to forsake his fellow-believer unless there is a shar’i reason for doing so. 
The Prophet  (peace and blessings of 
    Allaah be upon him) said: “It is not permissible for a Muslim to forsake his brother for more than three days.” Narrated by al-Bukhaari, 6065. The 
    sin is more serious if the forsaking for no reason involves a son, mother, brother or other relative, because in that case he is combining two 
    sins: forsaking a Muslim and severing the ties of kinship. 
Shaykh al-Islam Ibn Taymiyah (may Allaah have 
    mercy on him) said: 
The parents have no right to force their son 
    to marry someone he does not want. If he refuses he is not being disobedient; it is like forcing him to eat something he does not want. 
    al-Ikhtiyaaraat, p. 344 
Based on this, what you did was not a sin, but you have to continue to honour your mother and 
    uphold the ties of kinship with your sisters as much as you can. Try to reconcile with them. Go to your mother, kiss her head and hand, for she 
    only wants you to be happy. Tell her that you are happy and ask her for her approval. 
Do the same with your sisters. 
If they continue to cut you off, then ask 
    Allaah’s help and continue to honour them and uphold the ties of kinship with them. Remember the words of the Prophet  (peace and blessings of 
    Allaah be upon him): “The upholder of kinship ties is not the one who is kind to them if they are kind to him, rather the upholder of kinship ties 
    is the one who, if his relatives cut him off, he upholds the ties of kinship with them.” Narrated by al-Bukhaari, 5991. 
We ask Allaah to set your affairs straight and those of all the Muslims. 
And Allaah knows best.