Ex thinks he deserves another chance. Advice

I finally left my ex of 6 years because me and our kids deserve better, he didn’t man up for his family and still acted like a teenager with no responsibilities. This went on for 6 years and 2 kids. He was a complete asshole. Since I’ve left it, I get messages every single day saying he ‘finally realises’ we are what he needs and he’s ready to man up. He says this every single time I try to leave, but this time I’m serious I’m hearing it even more. He doesn’t understand that I wasted 6 years and went through hell and back for him, he thinks that him finally realising now is good enough to want me back. I know he isn’t a stupid man, but the way his acting now is really dumb. I’m pretty sure he has narcissistic ways or is mentally incapable of understanding common sense. How do I deal with someone like this, to make him understand. It’s so annoying but I cant be a bitch and cut him off cause I want to keep things civil for co parenting. Please help!!