I´m happy that people are being honest, even people who say they would die themselves would never think that way when the situation is happening in front of them.
It´s just human nature, your survival instincts take over and you do anything to survive.
I would press the button but i would make sure that i doom an evil man and save his children from his future abuse,rape and stuff.
Sorry but i have things to live for too, i live for my family, my relatives and my friends, i wouldn´t want them to suffer because i´m dead.
I would neither live with guilt nor regret, i would forget it and live through life, when my time finally comes, that´s when i will face what i´ve done and take the punishment necessary, i deserve it either way for taking a life.