The debt that is in joint names your wife should be paying anyway, so little will change there, except it will become joint again. The other debts could increase as creditors will add back lost interest and charges. They will then be able to chase you for repayment as they see fit.
Terminating an IVA is rarely a good move, but, to do so, stop paying and after three months the IVA will be failed. It will take another few months to get the termination papers, but your credit will still be shot until the 6th anniversary of the start date.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk