What to do?

So, i have a mans and yesterday he was pressured by his brother to take a huff from his w33d pen. of course, i got a little mad at him but more mad at his brother. i told him that if i hear that he smokes w33d again, i'm breaking it off, but then i regret what i said and apologised. we're okay now, but i don't know how to deal with his brother?