He sounds like someone with bipolar disorder, who had no personal discipline and then used his misfortune to justify completely surrendering to his impulses. Aerys died long before Jamie Lannister stabbed him in the back.
He'd have arranged a marriage between Cersei and Brandon Stark, tell Jaime that if he ever sees him near Cersei again he'll have an accident and probably spend more time with Tyrion while trying to find a new wife.