I love Jack, and I do not think any amount of craziness under pressure will change that. I think that for 90 something days he has been the leader,doctor,good guy, and after three attempts to get off the island were destroyed by Locke he went a little crazy.

1. He has seen his dead Father, the person whose death he believes he is responsible.
2. He has delt with numerous deaths of which he couldn't help, and for Jack that is not acceptable.
3.He let the woman he loves play with his heart for what seemed like forever, and then choose a man that was his nemesis early in the show over him. Which brings us to Sarah, who also left and chose another man.

He has been running around the island trying to keep everybody safe and together, and dammit he is tired!
Cut him some slack! Locke has been attempting and most of the time has accomplished his goal in stopping all of Jack's plans. And I'm not saying that he wasn't right in trying to stop them, but Jack is concerned about getting people home, and he is doing what he thinks is right. In Jack's mind he is doing what is best for the group, and he is willing to do anything to accomplish that.

I still love you Jack.

__________________
" I push this button every 108 minutes, I don't get out much."

"Theres a time for living low down, theres a time for getting high. A time for peace, a time for fire. A time to live, a time to die."

The real art of conversation is not only to say the right thing at the right time, but also to leave unsaid the wrong thing at the tempting moment.