I’ve learned to stay out of situations like this over the years, everything is always personal, everyone has a stake, and hardly anyone every really admits (often even to themselves) what’s going on. So I’ll give you what little advice I’ve given to others in similar situations, take it at your own risk. It’s about what’s best for the kid. Not for you, not for your ex, not for anyone else with a stake, but what is best for the kid. Remember, he’s only 13, it’s your job to worry about it. Talk to him (yeah, it’s tough at that age) about it, but don’t make it about your concerns make it about him. Don’t forget he’s developing a self image and will want to protect it, but there’s an awful lot he’s not old enough to understand beyond the immediate/near future. The more he feels it’s his choice and that you are genuinely there to support him and respect his opinions not protect or judge (bad things from adults when your 13 if I remember my youth correctly), the better it might go. But he’s your kid, not mine, I don’t know him, nor does anyone else, the way you do. Regardless, good luck.