reprehensible - Describing behavior, actions, or conduct that is morally wrong and worthy of disapproval or condemnation.

Though he told people not to repeat it, it was reprehensible for him to spread rumors about his colleague, knowing it would damage her reputation.
wedge - A piece of material with a thick end that tapers to a thin edge, used to split, support, or secure things; also something that forces separation or division between people or groups.

The disagreement drove a wedge between the two longtime friends, and they really didn't enjoy spending time together anymore.