You should tell your ex the truth about your feelings.
Jack's ex wife asks him what happened in their relationship.
Jack wants to end the conversation.
Jack honestly points out the flaws he had with his ex-wife.
Jack tells his ex wife that it was all his own fault and that he's just a terrible husband.
His ex-wife thanks him and tries to improve for her next relationship.
His ex-wife has three more failed marriages because Jack didn't tell the truth.