Jack didn't forget anything. He lost everything. It set him down a different path than the one the Moon had intended. A darker, more violent one.

How many times can you kill a man before you ultimately change who he is? How many times can you kill a man, before he ultimately changes who you are? ~*~ Obi-Wan, desperate to see his mission through and knowing he's dying already, sells himself to a vengeful mandalorian if only he'll finish the job in Obi-Wan's stead. That goes about as well as you would expect. (It doesn't.)