I am about to get married, what can I do to protect myself?

Thank you for your question. You are in a predicament for certain.  You’ve invested 5 years of your life into a relationship that is tainted and you still have the stamina to resurrect the trust and love you have in him.  The good news is that he is in therapy and therefore he recognizes his foibles.  As a legal matter, the marriage document does not make you a joint debtor unless you co-sign or otherwise agree to assume those liabilities.  A pre-nuptial agreement is the way to protect assets for sure.  If you have significant assets you should get a family lawyer to prepare such a document prior to your marriage.  If not, be sure to maintain separate bank accounts and DO NOT co-sign any loans and/or assume any debts he has already incurred.  Ultimately should he default in any payments, the creditor will pursue his assets including wage garnishments and bank levies.  But it cannot and will not seek payment from you.  So remember to keep a separate checking and savings.  I sincerely hope your marriage will be a success otherwise.  Just so you know every married couple has issues and debt.  You are not alone but at least your husband to be is seeking therapy.  Be sure you are included in that!  Best wishes.