HE started the latest round of feuds. Things settled down and then he went on the attack and I don't fault Victor for seeking revenge. Let's not forget why Victor brought Patty to town with a new face--it was retaliation for Adam and Jack writing the book and attempting to frame him for murder!
Jack has lost his family over this. His sisters have told him they want no part of this feud and even the loss of Colleen wasn't enough to get both men to realize...enough was enough. Jack isn't beneath using his nieces. He used Colleen and also Abby to get what he wanted.
I haven't seen today's show and don't blame Jack for the collapse, but I sure as hell blame him for holding on to this vendetta and constantly trying to one-up Victor to fix something that happened 15-20 years ago. He could have stopped at BON (something he has been dying to get his hands on) but noooooo he won't stop until he has EVERTYHING and that is why he will end up alone and possibly the loser--again.