over reacting??

Hope
My boyfriend used to smoke every now and then before he was with me, since he's been with me he hasn't, but rang me today and told me his friend gave him one, so he smoked it. I've told him before not to do it, and he agreed. It's not good for him, he has asthma. I got cranky with him, I feel like I'm over reacting, but I really can't stand smoking.