Kat Von D claims Jesse James cheated on her with 19 women during their "toxic relationship" ... this according to a rambling confessional she just posted to her Facebook page. Kat never mentions specifically if that's why their relationship ended, but she does say she deserves a big fat, "I told you so," from everyone: "You all were more right than you'll ever know."
Jesse's not talking, but we're told the two of them have been broken up for months, which makes the new "revelation" a little weird. Don't know if it's just coincidental ... but her show was also given the axe a few months ago, so it could be a grab for attention.