If the defending hero get killed by 1 enemy, and the other two heroes are already exhausted, will the other engaged enemy still attack? How do I resolve this situation? Treat it as undefended and add wounded token to a hero (that already exhausted?) Please help….

The other engaged enemies that have not yet attacked this turn will then attack, and since you don't have any defenders, they are considered undefended attacks.

Wow, then the exhausted hero will get wounded too…that is …so…arghhh….

Anyway, thank you for the answer.