If I ever wrote a story where the villain killed himself in front of the hero the ending would be...
He looked at him with a smile, a smile which is filled with pain and sorrow but no regrets he kept the revolver on his forehead as he looked at the person in front of him and spoke,
"I don't want to kill you as you are my life and killing you will make my world empty and I can't live in a world in which you are not there!"
And with this gunshot is heard in the room killing the man an instant as he has a smile on his face.