After 5 years, my ex still has feelings for me 🤦🏻‍♀️ and it’s affecting our kids

My ex and I have 2 kids together. I left him over 5 years ago for various reasons. One of them being he would constantly talk/flirt/text with other females. I gave him multiple chances until I realized he wasn’t going to change. I’ve had 3 boyfriends since. The first one I didn’t bring around my kids, the 2nd I did, biggest mistake of my life 🤦🏻‍♀️ and the 3rd just met my kids (after 10 months of dating).

Every single bf, my ex would be upset about. He would completely change and be an asshole. Now with the guy I’m with, things are serious to the point where we’re planning on moving in together by December. My ex is a complete asshole to him and very immature , always calling him names even around our kids. That’s what upsets me the most, my kids are scared to tell him anything about my bf because they know he’ll get upset. They’d rather lie to him, which I’ve told them is not ok. But I get why they do. I’ve tried talking to him, I’ve tried reasoning with him and telling him what he’s doing doesn’t affect me but it does affect our kids and he doesn’t realize how much. His family/friends have even told him that he needs to get over me and just let me be. Idk what else to do. I don’t care what he tells me or my bf, although I wish he had some respect since my bf hasn’t done anything. But I do care what he tells our kids. Im running out of things to tell him. Any advice? It’s very frustrating and I’m just so annoyed now. 5 years of this 😒

We share custody so taking them away isn’t an option unless I go through the court which I know will get ugly.