Praise be to Allah.
Maintaining good relations with people is something for which you are to be commended and is a good attitude to have. It is not permissible for your maternal aunt, her husband or anyone else to try to spoil these good relationships.
However, it is essential to note that the maternal aunt is of similar standing to the mother, and she has rights that are prescribed in Islam under the heading of maintaining ties of kinship and kind treatment. Hence we advise you to be patient with her and to advise her and her husband, and to use whatever you can of permissible and Islamically prescribed means to make her stop her evil actions by means of wisdom and beautiful exhortation. There is nothing wrong with seeking the help of those who you hope can influence her with sound advice.
But if mixing with them will lead to negative and evil consequences, then keeping a distance from them is what one should do, but that should be done without severing ties altogether, speaking ill of them in their absence, reviling them and other acts that comes under the heading of bad manners that Allah has forbidden.
Rather one should strive to protect oneself against evil, harm and mischief as much as possible; in that case it is sufficient to contact her by phone in order to check on her and ask how she and her family are, and so on.
You should treat them with kindness and use a subtle approach in protecting yourself from their evil and the harm they cause to you and other people.
If shunning them will have an effect on them and stop them from doing evil, then there is nothing wrong with shunning them.
Shaykh al-Islam said:
If a person openly commits a major sin, then it is justifiable to punish him by shunning and other means, even if shunning him may serve one’s own interest, thus serving the shar‘i interest as much as possible.
Majmoo‘ al-Fataawa, 24/286
But if the harm affects only you, then try to put up with your aunt’s annoyance as much as you can, and adopt a gentle approach towards her, whilst protecting your religious commitment from her and her husband.
It was narrated from Abu Hurayrah (may Allah be pleased with him) that a man said: O Messenger of Allah, I have relatives with whom I try to keep in touch, but they cut me off. I treat them well, but they abuse me. I am patient and kind towards them, but they insult me. He said: “If you are as you say, then it is as if you are putting hot ashes in their mouths. Allah will continue to support you as long as you continue to do that.”
Narrated by Muslim, 2558.
Shaykh Ibn ‘Uthaymeen was asked:
My paternal uncles hurt me by gossiping about me to other people; what should I do with them? Should I cut off ties with them?
He (may Allah have mercy on him) replied: Do not cut off ties with them. The more one upholds ties even though the other party cuts him off, the better it is. Do what is required of you in terms of upholding ties with them, and leave the matter of their cutting you off to Allah, may He be glorified and exalted. You will be rewarded if they annoy you and gossip about you to other people, because that will only increase you in reward, and on the Day of Resurrection you will take from their good deeds (hasanaat), if you did not pardon them.
End quote from Fataawa Noor ‘ala ad-Darb, 12/468
It should be noted that severing ties of kinship is a major sin and it is a very serious matter in the sight of Allah. Allah, may He be glorified and exalted, says (interpretation of the meaning):
“Would you then, if you were given the authority, do mischief in the land, and sever your ties of kinship?”
Muslim (2556) narrated from Jubayr ibn Mut‘im (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said: “No one who severs ties of kinship will enter Paradise.”
You should uphold ties of kinship as much as you can, whilst protecting yourselves against their harm and annoyance. Do not give them any opportunity to interfere in your lives and spoil relations between you and other people; rather you should tell them not to do that; either they will refrain or leave you alone.
May Allah make things easy for you and protect you from the evil of what you fear.
And Allah knows best.