What is the advice for dealing with the father of a wife divorced irrevocably (by three pronouncements) during a period of purity in which intercourse occurred, who remains angry and avoids the divorcer, despite attempts at apology and reconciliation, and is temporary avoidance of him considered a wise action?

A man has no right to shun you merely because you divorced his daughter, as divorce is a legitimate right for the husband. As long as you strive to maintain ties with him and he turns away from you, there is no blame upon you, and he is the one who incurs sin for severing kinship ties. Continue trying to connect with him, and if it is in your best interest to avoid sitting with him in some gatherings, there is no objection. You can mediate through some wise people to explain that his shunning has no justification and that he is severing kinship ties. It was reported from Abu Hurairah that a man complained to the Messenger of Allah, peace and blessings be upon him, about his relatives who cut him off and mistreated him. The Prophet, peace and blessings be upon him, said to him: "If you are as you have said, then it is as if you are feeding them hot ashes, and there will always be a supporter from Allah against them as long as you remain upon that."