It's tough to deal with teenagers. Hang in there, they grow up eventually. My 16 year old was 14 when he figured out that we were poly, and he was already good friends with the couple who make up the other half of our quad. Well, being friends with them didn't help even a little, he had a major hissy fit if I even tried to hug Sunday, my other male partner. My son stopped talking and confiding in Asha, my female partner. He told me that love was meant to be shared between two people. I told him that was fine for him but I felt differently.
I just try to keep on keeping on, living a good example and being a good, calm mom who isn't ashamed of her life. I say the words, "That's none of your business" a fair amount, and try to make sure that everyone gets involved in family activities as often as possible. I *think* it's working. We certainly seem to be having more "good" moments than bad ones lately.