You should balance it. "Just a spoonful of sugar makes the medicine go down" as Marry Poppins would say. But if there was ever a clearer need for "obedience training," it's this. Not so much that she has to obey, but it's simply not acceptable for any person to rag on you seriously all the time.

Actually, come to think of it that goes double for that 'friend' of yours. The problem here is you're allowing people to belittle you without any kind of consequence to themselves. I know this is only pickup, but consider that 200 years ago, men would draw swords or pistols and fight duels over this sort of thing. Nowadays we have to duel with our wits instead of weapons, at least if we don't want to get shot by some hood for no particularly good reason. I like the "treat him like a 12 year old" idea.