How do I deal with my wife's father whose known to have no respect for people who are more educated than him in which he consider any objection to his point of view a sign of no respect from the person who objected his point of view. In many cases he lied, stabbed people from behind by talking about them. I always try to indicate to him that he is making a big sin and if that continues I will cut off all communication with him. Now the problem has affected my marriage since his daughter who is my wife is unable to play a fair role in bringing about any genuine change. I have indicated to my wife that we should move away since they are living next door to us. Every time I mention that to her, a fight takes place; I end up leaving the house to prevent any escalation. I have been living in the USA for 20 years and since my wife's parent came to visit us, my life has changed due to many bad morals lying, worship of money, gambling, some morally bad behaviors I have witnessed from the parents and their son who is living with them .I am trying to avoid the worse case scenario (the divorce) which will destroy the lives of my three children. I greatly appreciate your help.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

You have to remind your wife's father of the Prophet's (Sallallahu Alaihi wa Sallam) Hadith: "The best of you are those whose morals are best" [ al-Tirmizi ].
Another Hadith from Abdullah Ibn 'Amar reads: "By nature the Prophet (Sallallahu Alaihi wa Sallam) neither talks indecently, nor did he listen to indecent talk" [Reported by Imams al-Bukhari and Muslim ].
A third Hadith reads: "I like those who have the best manners from among you" .
In the Sahih Book of Ibn Hibban and Sunan al-Tirmizi from Ayisha (Radiya Allahu Anha) who said, when she was asked about the morals of Allah's Messenger (Sallallahu Alaihi wa Sallam) with his family: "He was the best in morals. He did not talk indecently nor was he clamorous in markets. He did not retaliate for offence, but forgave and overlooked" . al-Tirmizi said: 'This Hadith is good and sound' .
Another Hadith reads: "On the Day of Judgement the dearest and closest to me, as regards my company, will be those persons, who will bear the best moral character, and those among you, who will bear the worst moral character, and who talk with affectation and are given to boasting, will be the most repugnant to me, and farthest from me on the Day of Judgement" [ Ahmad , Ibn Hibban , al-Tabarani and al-Baihaqi from Abu Tha'labah ].
It is recorded by al-Tirmizi and others from Abu al-Dardaa who said: "I heard Allah's Messenger (Sallallahu Alaihi wa Sallam) saying: "Nothing is weightier in the scales of a believer on the Day of Judgement than his good behavior, and a believer can achieve the position of one who regularly fasts during the day and spend (the night in) prayer through his good manners" .
Then, you have to advise this man (your wife's father) by presenting him a book, some recorded material and so on.
Also, you have to avoid retaliation, but treat him kindly and politely. It is better to remain in your house and to have good relations with him. This might lead him to have better behavior and to accept your advice. You can decrease relations with him to avoid any form of quarrel or difference.
If you wish to leave to another house (also we do not recommend that) your wife's duty is to obey you. And avoid thinking of divorcing her since divorce is the last solution, i.e. if other solutions fail.
We ask Allah to grant you success, in word and in deed.
Allah knows best.