I don't know that there can ever be true revenge against an enemy like the Borg and the pursuit of it nearly drove Jean-Luc to his death.

(And not just him, the crew too, and all of Earth.)

He met her. The Borg Queen. Like termites or ants, the hive all circle around her. But even when one Queen dies, that's not the end. There are other hives, other Queens - so although he could look this one in the eye, talk to her, kill her, it wasn't enough to destroy them, not completely.