I have been dealing with a controlling/nosey/stalking ex for years now, and my advice is this. Always remember that you have a limited amount of energy, choose to use your energy on the things you can control, and don't waste it on the things which you can't control. For example, your ex is not doing your son any favors by asking him all about you, but he (your ex) has issues and have no control over that. What you can control is how you interact with your son(s). If you catch yourself asking lots of questions about your ex to your son, you can say, Sorry, I shouldn't be asking you all of these questions, it is not right. This shows your son two things, a) you can admit when you make a mistake and b) it is not right for him to be in the middle of his parent's relationship (and you've so without bashing Dad - if he says but Dad does... you can simply say you don't agree with Dad).All of this is easier said than done, but by reminding myself of this daily, things have gotten better and I can focus on not letting my chaotic ex take over my life anymore. In general, divorced or not, we should all live our lives in ways that we can be proud of. As long as you do that, it shouldn't matter what ex knows, and don't waste energy thinking about it.