the only other possibility is Locke but I think Jack would have considered Locke "an old friend"Jack and Locke have almost always been at odds with each other. Even when their goals were similar, they disagreed about the best way to accomplish those goals. At this point, I don't think Jack considers Locke a "friend." Heck, the man threatened to shoot him last night!
Ben was finally telling the truth last nite to Jack about Naomi and the "bad people." We know from his discussion with Kate that he has come to realization that he should not have left.
That may also be a matter of perspective. Kate didn't seem at all unhappy about having left the island. Leaving the island may be bad for Jack, but that doesn't mean it's a bad idea for anyone, or even everyone, else.
Slice n' Dice's Sigpic Chop Shop 2004