Is the vision mentioned after performing Salatul-Istikhara, in which a person was described as "one of those who associate with Satan" due to a divorce oath of questionable validity, a work of Satan or does it have an interpretation related to the reality of the marriage, and can it hold some truth?

A dream is from Satan and should not be relied upon. As for a vision (ru'ya), it is from Allah and can be a source of comfort. It may indicate good or warn against evil, and the vision of a believer is a part of prophecy.

People are of three types regarding visions: Prophets, and their visions are all true; the righteous, and most of their visions are true; and others, whose visions contain both truth and jumbled thoughts.

So, if one of you sees something he dislikes, he should spit lightly to his left three times and seek refuge (with Allah) from its evil.

Istikhara (seeking guidance from Allah) is performed for matters where one does not know the right course of action, provided the matter is permissible. It is not for determining the validity of a marriage, but rather by asking people of knowledge.