Not aibu but posting for traffic.
Got a letter about an old debt from a previous address where I lived with my exH. It's in both our names, and I called straight away to set up a payment plan. I've since then asked exH to pay his half of the debt, and he's straight out said no because they didn't send anything to his address, despite me showing him the letter with his name on.
Is there anything I can do so that I don't end up paying the whole thing myself? For context, he's on UC and doesn't work but I am too, due to being a full time carer.