Forum:Kycoo VS Stardust VS mirror force

Question 1-I BC'ed a stardust from my opponent. My opponent used mirror force but I attacked with another monster,Kycoo-kun. I release my stardust and is effect of kycoo removes stardust from play? and Question 2-How the non-sportmanship comes to my duel. After I removed his stardust,he reveal his BTH and he said that he BTH'ed my Kycoo so he will win. That was 5 minutes after I summoned kycoo And he said that, I have done this before. (Which I still be a NooB 5 years ago!!!)

Please answer my question, how should he do? (He's also my little bro, after all.)