While Kat does not address the specifics of the breakup in her tweet, it's a reasonable guess that it was her idea, "I am no longer w Jesse, and out of respect for him, his family and myself, thats all the info I'd like to share. Thanks for respecting that."
While it's probably bad karma to rejoice in another's relationship woes, I can't seem to help myself. Jesse James is a vile and foul individual, and from all the evidence I've seen, incapable of offering true and caring love to another person. Three failed marriages is a pretty good indication that one is not committed to the sanctity of marriage, and when you throw in his extremely questionable behavior and his need for negative attention, it's not hard to come to a negative conclusion.
James publicly humiliated his third wife, actress Sandra Bullock, back in 2010, just weeks after winning her first Oscar for The Blind Side. Tabloids broke the news that James had been having an affair with tattoo model and stripper Michelle "Bombshell" McGee and the fallout tainted her happiest moments, which included a planned adoption of an infant son, Louis. Instead of disappearing forever in shame, Jesse went on the offensive and wrote a memoir, using Bullock as fodder to sell books. He also continues to abuse her in the tabloids whenever the opportunity presents itself, even when referencing his current love life.
If ever there was a celeb deserving of heartbreak, condemnation, and public jeering, it's James. So count me as one of the people who will be celebrating another failure in his life. Congrats Kat, your life just improved exponentially!