First - This fight shouldn't last too long (round-wise).
Second - Be glad it wasn't a Pyro-Hydra.
Third - You actually provided the best thing a tank of your type can - You took the full bront of the badguys assault while everyone hit it hard, and YOU don't have to worry about dieing from it. It's next turn will be much less happy for the good guys.
Besides, there's not much tactics a straight-out melee character can use in a situation like this. Even if you hadn't charged and taken the -2 ac penalty, it still would've hit you enough to drop you. and if you'd taken the action to set your shield instead of attacking, it would've breath-weaponed last round, probably killing somebody.