Has anyone dealt with a narcissistic partner?

Not with a partner but with a parent and a sibling. It's rough, basically its' worth it to bail but if you really, really have to stay then idk you can go two ways either fight it and try to keep them from getting too big but that's a heap of stress and a battle every day. Other way to go is ignore them whenever possible but that can also go wrong if they decide to get big and get abusive thinking you being unengaged is submission.

You say you gotta stay for the son, but keeping him around that is worse than a lot of other things, because it could stick with him for life to have that influence how he grows up. That's what happened to my sister, she got traumatized for life. Me and my other siblings too to some extent but one sis got it the worst of all of us.