AIO when my husband asked for a threesome…

Me and my husband have been married for 1 years, He is turning 28 this year i’m turning 22. He has been addicted to porn since i’ve known him, and to some that is a huge deal, to me He is open and honest that he does it but I never see it so it hasn’t bothered me too much, as i watch porn myself from time to time. Until the other night he wants to have a threesome, but he wants it to be with a guy and he wants to watch… he will participate some but he thinks he will get off on watching me “feel good”. I have no idea how to feel about this… i hate the idea. I dont even know how to feel. He is a very sexual person, we have sex almost every night. Do I look into sex therapy for him? Im at lost of words. I screamed at him and told him absolutely not and that i feel he dosnt respect or love me am i overreacting?