DP is off work at the moment. He suffers bipolar disorder and I have assured him I support him to stay away from work until he's feeling ready to go back. This means I take on full responsibility of the finances. I also control the finances quite tightly as he has a habit of buying lots of useless things all of a sudden which has got us into a bit of debt with credit cards and such. I will always give him money but not for iphones and computers etc.
So, yesterday we were at MILs house and DS had left his coat on the living room floor. I was just about to tell him to pick it up when DP ran upto it and booted it across the living room. It landed on a coffee table in the corner of the room and knocked an old Victorian style lamp over totally smashing the globe thing on top. MIL was horrified and ran over to survey the damage. DP was in hysterics. He was laughing so much he couldn't talk. I was mortified and told him it had smashed (assumed he hadn't realised) and this made him laugh even more. He had to leave the room, he had tears rolling down his face. This made the kids laugh who then got shouted at by MIL. I know it wasn't nervous laughter as he was still laughing about it when we got home. His excuse was "but it was fucking disgusting anyway!"
MIL is now wanting £70 to replace it. DP is assuming I will pay and I have refused. I have now got it thrown in my face that I promised I'd support him and I don't understand etc etc. MIL is also thinking I should pay as I'm working and have recently bought new things for our house so "its obvious I can afford it".
Really don't know what to do. Realistically he has no money to pay it and it DOES need paying for! AIBU to dig my heels in and refuse or do I just have to suck it upm grit teeth and pay??