Simple. I would push neither and find a way out, kill the person or persons who made me play their stupid little game and make them suffer, very very slowly.
^ I would nopt be able to cope with killing people just because of a button press. I believe there was a psychological study done in the 60's that had something similar. Two volunteers were chosen. Both sat in different rooms; one had to ask questions and the other had to answer. The person asking the questions would shock the other if the right choice wasn't chosen.
http://youtu.be/gZnronVFyDE
I wouldn't kill my friends and family, and I've a fear of death in general, so I wouldn't commit suicide.