My motto is "A problem shared is a problem solved", and you clearly need to share your difficulties with your partner to reach some common understanding about the situation, and to help him understand that things have to change from now on with regard to his spending.
It may also help to chat informally to an insolvency practitioner or debt management expert to ascertain what options you really have. Importantly to determine whether you have a debt management problem or a debt problem. There are distinct differences, and caught early you can work to avoid the former turning into the latter with some simple rethinking about your lifestyle, aims and goals.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
To have me propose an IVA for you, please visit:
http://www.melaniegiles.com/ivaEnquiry.asp
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http://www.iva.com/iva_companies/IVA_Advice_Bureau.asp