Try reading up on Buddhism. It's also something I learned a long time ago in therapy, before SO. Somehow I managed to forget it during R1 with SO. Probably because he was being such a control freak, and our R just turned into one big power struggle. Bad news.
The bottom line, Mathilda, is that the only thing YOU can control is YOU. You can't control anyone or anything else. I suppose having teenagers helped me understand this. Any control parents think they have over their teenagers is a totally facade. They can and will do what they want to do. The question is whether you've taught them well enough by the time they get to that point.