Is the questioner burdened by the sin of the dispute that occurred between him and his colleague, which was orchestrated by a third colleague in cooperation with the direct manager, and what should he do?

Harming a Muslim and conveying speech to incite grudges (slander/tale-bearing) is forbidden and a major sin, indicative of the malice of the one who commits it. The slanderer will not enter Paradise. Slander is the disclosure of what one dislikes to be disclosed, whether it is a statement, an action, or a defect. The slanderer must be advised, and the ugliness of his action must be explained to him, and he should be encouraged to foster harmony so that an enemy may turn into a friend. Boycotting a Muslim for more than three nights is forbidden, and whoever boycotts his brother for a year is as if he has shed his blood, unless there is a legitimate religious interest, such as reforming religion, or addressing immorality or innovation. One should mend the relationship with the colleague and not fear people, for Allah is more deserving of fear, and whoever trusts in Allah, He will suffice him against the plots of schemers.