I'm just going to jump in here...

1. Yes, everyone (especially his family) will forever resent him. I think he just needs to be alone for awhile. He seems to have temper problems (most likely the reason why he was being home-schooled prior to this event), and I think being alone will be the best thing for him, as there is nothing to get mad at.

2. irrational, of course. But it's apparent that he has some mental problems, so it seemed rational to him, obviously.

3. I think he regrets it, definitely. The poor guy was crying on the phone, after all. And to be honest, I'm surprised he didn't kill himself.

As a form of punishment, I don't think prison is the right answer for everything. He'll probably be sent to a rehabilitation sanctuary (a.k.a. the best route). I hope that they don't send him to prison, that won't do anything, he'll probably just end up there again like a lot of people. He needs to be helped, so hopefully later in his life he can get some sort of job and a family.