Kids are smart. A lot smarter than a lot of people any where on this board give them credit for. And your kids aren't babies. They are 12 and 16. They are in the middle of battling their way out of childhood and into adulthood. Divorce or no, teens are defiant. They say mean things to the people they love the most. They do rebellious things for the sake of rebellion. They see how far they can push boundaries to see what their limits are, to see what your limits are, simple to stretch their wings. Shop lifting is incredibly common in teens. Lying, all teens lie. Self harm, super common. Experimenting with drugs, don't know if he did that, but that's also completely normal teen behavior. Disappearing and not telling you where they are going, yup typical teen behavior. It hurts as a parent watching your sweet babies become raging hormone monsters. It's frustrating, rage inducing, and deeply saddening when they make you feel helpless or like their behavior is completely out of control. But the reality is their behavior is as much in your control as you want it to be.
They are going to do things that need to be corrected immediately. Speaking to you like that, well let's say your boy is lucky I'm not his mom. We'd be done with that after the first comment. Absolutely not. You are in charge of what you allow. Would you let your ex speak to you like that? A stranger? Your kid doesn't get kid glove treatment because he's a child of divorce. That's not how this works. The likelihood that he's acting out because of the divorce and not because he's just an angsty defiant 16 year old boy is pretty slim. Also teens are going to do things that you really should just straight up ignore. Not every hill is a hill to die on. Sometimes you need to act like them and just roll your eyes and go about your day. Surviving teens in or outside of a divorce is difficult. But a lot of what you're doing here is attributing completely normal teenage behavior to your ex and the divorce. Narcissist or not, manipulation or not your kids are too old to be fully puppeted by him. And your ex is your ex, evil, sociopath, narcissist he may be, but he's not a god. He only has as much control as you let him have. Even if he's using your kids as pawns it's a game he's playing with you, not them.
The only way for you to get through this with your relationship to your children in tact you genuinely have to separate your issues with your ex from your issues with your kids. At this stage it's way too complicated to suss out the correlation and/or causation of the divorce and your ex on their behavior. You need to get into therapy if you aren't. You need support and tools to traverse this. You have a lot on that plate of yours and a non-bias sounding board to help you process this stuff could really go a long way. You also really need to establish clear boundaries with your kids. What is and isn't acceptable. It's not acceptable to just disappear as a 16 year old. It's not acceptable to tell your chronically ill mother she should get a real job. It's not acceptable to commit crimes. It's not acceptable to rage when you would've been more than happy to have a conversation. And yes, laying down the law could push them into the arms of their completely trash father, but that's neither here nor there. That's a bridge you'll have to cross if you get there. Some kids need to learn things the hard way. And if thinking the grass is greener with dad, you may have to just let them learn that. If the lesson is dad is not who he pretends to be, I'm almost positive they will each have to learn that the hard way.
You are not the first parent to navigate this sh!tshow. I've had more than one friend pack their child's belongings up and let them know if dad/mom(although less common in my circle) is so fantastical and amazing and the best parent, person and human to walk this Earth ever by all means go live with them. I've only ever seen maybe 2 actually go for it. And I've yet to have seen a kid who didn't regret their decision in less than 30 days. I saw one kid pack her own stuff and all her mom had to say was "And where do you think that's going to go in your dad's house? He doesn't even have a room for you. You sleep on a couch. BTW does he even know you're planning on moving in?" He didn't show up to pick her up that weekend and called to cancel like 3 hours after he was supposed to get her. Sh!tty people never fail to show their colors, even narcissists. And some kids refuse to learn life lessons through critical thinking, they need their hearts broken and hopes dashed to accept that the fairy tale version of reality they've had in their head was completely off base. It hurts like hell to not be able to soften the blow for them It's hurts like hell to not be able to get them to understand things holistically enough that they don't have to learn the hard way. But that's the nature of children. No one will ever bring you more joy or more pain. And it's our duty to let them find their way, be a firm hand to guide then and a soft place to land when they fall flat on their faces.