Say something or wait for him to come to me

My 15 year old logged onto Facebook on my laptop and when I saw it up I saw a text message that startled me. So I've had feelings him and his girlfriend were sexually active. She's 16 almost 17. It was from a guy saying that he's not trying to cause shit but he has had sex with his girlfriend but she told him they broke. He said he donates plasma and he got a call from his center saying he showed up HIV positive and is now permanently differed from donating. He's waiting for ig his second results but when he found out that they were still together he decided to let him know... My son never responded to just message. Just saw it. Idk if I should talk to him or wait for him to come to me.