People asking why and how...dude snapped YEARS AGO! For him there was no other "solution"! We don't have to understand or justify! It's not right or wrong, but simply his decision! Maybe if he returned several years before the hero arrival, he would have time to heal and take another route! But since he basically just came from a world where he was constantly abused, another month of abuse seems it doesn't even faze him! He just to see everyone involved suffer hell! Would be interesting if in his revenge actual innocent people get dragged in, making him nothing better then the abusers!