Thank G-d he is healthy and happy. But please step back. You do not have the right to tell another adult how to lead their life. You can change the lock if you don’t want him to come back, or ignore him, or welcome him, as you see fit (let me stress YOU). And so on for the internet, the liquor and everything – you are the parent and you decide. But you can’t try to manipulate him by using your feelings, because as you can see, he is doing the same to you. I realize you are worried for real when he leaves and does not tell you where is going, when he’ll be back, and cellphone is either off or you don’t dare calling. But you can’t afford worries. People who G-d forbid have bad diseases or have a child with such problems, don’t have time to worry, 24hrs a day are not enough to finish all they have to do. People did not worry during the war, they used that energy to do everything in their power to survive. You have to do the same and be strong. And, I realize that, like anyone else in your position, you are less than delighted about his lifestyle, but please don’t use light-heartedly expressions such as “he ripped my heart”, G-d forbid there are parents who have children who get in trouble with the most serious criminal laws, or in the “best” case, admit having chosen a lifestyle such as advertised by the Jerusalem parade.
I am not denying the possibility that some RY or teacher did something wrong to him (like you, me and everyone else, they are not perfect, and, your son is not perfect either) but even if it were so (I think something happened, but it is much less of a big deal than you think), yet you should not IMHO justify your son using it as an excuse. With this outlook, someone, even if surrounded by perfect tzaddikim, can say the same, can even blame G-d for “picking” mitzvot and neglecting some. You never heard about someone dying while doing the mitzvot that bring long life? I know personally such stories, besides them being recorded in the Talmud. But this is not how we are taught, is it. There are things we don’t understand, and when we don’t, we leave it at that. The more you feed into his delusions and the more he’ll be unhappy. He is happy with his “friends”, yet they don’t treat him with velvet gloves, they give him harsh “mussar” (within their outlook), they hold him responsible. Perhaps there is something to learn from that.
Shabbat Shalom to you and all your family