Welcome to the forums, it is nice to meet you here.
It sounds like you are in quite a predicament with your ex, and I understand you are feeling really scared and upset about this. I'm not quite sure what you are able to from a practical perspective, and I hope there are others who perhaps may be able to share some good advice, because it sounds like a really terrible burden to be under.
It's so important to have independence from your ex but it seems like you are tied to him at the moment. From what I understand, you do not want to, or can't, stop the shared loans, is that right? To be frank, it's going to be very hard to get peace of mind while you are still financially tied to him like that and it sounds like he's not going to change. It also sounds like he's living in your home with his new family, and I am not sure if you are also living with them?
Still, I understand you are feeling really defeated and stuck, and I can see that your ties to him are causing a lot of stress for you. Have you sought any professional help, either financial or legal, to get some independence back?