Zuko was clearly far from being pleased with his sister for her actions but did not seem to show much resentment for that, even commenting he actually felt good for her restored mentality.
But Mei didn't marry Zuko.
V MJOLNIR armorThe Mark V MJOLNIR armor. Created parallel to the SPARTAN-II program by the Office of Naval Intelligence's Materials Group, the Mjolnir armor is the most advanced piece of tactical military hardware in human hands.
Silas took the cure and was just a mortal witch, who wanted to die. So as it currently stands, Marcel is the strongest species.