Starting from Breaking Off the Engagement and Building an Immortal Dynasty

I am a cannon fodder male supporting character whose engagement was broken off by the heroine. According to the plot, I will become evil, commit suicide, and be stepped on by the hero. I immediately agreed to break off the engagement and go to the border areas to build infrastructure. Three years later, the heroine came to me crying: The country is ruined and the family is destroyed, but only your city remains. Me: Sorry, my city doesn't support idlers.