This verse begins with a reference to a "gut feelng" which translated as "move with compassion" and "took pity". In Greek, the "bowels" were considered the seat of compassion. We describe this as "being moved" in a very similar sense. This words begins the sentence, setting up the rest.
The "forgave" is set up as a punchline by it phrasing, "And that debt? He forgave him/it." The last word is in a form where it could refer to the slave, as an indirect object, or to the debt, as an object.
Christ's Words in Matthew as a Guide to 40 Days of Prayer.