You are asking why he responds the way he does. He is a teenager that is not getting his way. He wants his cake and to eat it too!
You are not buying into his cake eating and he does not like it.
I do not think you have done anything wrong but in not being NC with him you are setting your self up for his tricks. If you don't want to hear his garbage then go dark. If you can bear to listen to it then you might want to set a boundary with him. But don't have any expectations that he will listen to you.
