DPS are responsible for managing their threat even when they outgear you.

If people are so confident that they aren't paying attention to your marks, then mark 1 enemy and tank it. Let them kill the rest. If someone dies, tell the group to start following your marks and managing their threat.

It sounds like you were pretty frustrated and weren't having fun, but since the healer raised you (after letting you die), you could have resumed tanking. Sometimes you encounter party hate, which is people saying or doing stupid things that destroy the morale of the party and can cause you to fail the dungeon. You're a tank, so you can tank party hate if you want.

If you don't want to take it, then tell people to manage their threat, follow your marks, and let you tank. If they won't, quit the dungeon. A 15 minute penalty is better than playing with people who aren't fun.