Just a small addition, maybe she should actually tell him how she feels and split on good terms. She is running the risk of him declaring bankruptcy/leaving the country then she will be liable for 100% of the debt. (sounds like he has lumped most of it on her anyway) Even with bad credit, there are lenders who will still give him money at a high rate, nothing to stop him doing a crazy loan and firing off.
This is a minefield your in at the moment, damned if you do and damned if you don't. Just make sure you look after your own interests first, sounds selfish but don't let one failed relationship bugger yours.