Jane,(posted 7460 days ago)I agree with David that you should seek professional advice, you could try Ahmed Butt of the Mary Ward legal Centre, the National Association of Mortgage Victims, the CAB, or a local council advice unit.
Bear in mind that there are free debt management plan providers available, such as Pay Plan, which I notice Simon Wiggins of debtquestions often recommends. Some people say that a BS/bank is more likely to accept a pay plan/lump sum settlement if it is organized through a third party like the MWLC, NAMV, CAB.
Also, the lender has 12 years to chase you and your ex (possibly indefinitely if an MJO has been issued), the CML 6 year voluntary agreement won't apply in your case see "Does this time limit apply to every case?" on the CML web page http://www.cml.org.uk/servlet/dycon/zt- cml/cml/live/en/cml/pub_info_dept
Be advised too that by making part payments this can restart the 12 year limitation period for you & your ex. See previous postings on acknowledging shortfalls. Good Luck.
Mark.