Wow, just wow! Where is the dad in this equation? And, what would his reaction be?
One morning, when my oldest was about 13 (many moons ago
), he was sassing me, following me down the hall, just yak, yak, yak. Well, my husband came barrelling out of our bedroom, grabbed "said offender" and very menacingly said, "You may think your talking to your mother like that, but your not. You're talking to my wife, and nobody talks to my wife like that."
That made quite an impression on him and I very rarely had any sass issues again. It also worked on the younger brothers because they watched the whole episode with saucer eyes, thinking, "I don't want that to happen to me!"
That kid needs a swift kick in the rear (metaphorically) from his DAD! His mom has obviously lost all control and credibility - a united front is needed!