A marital separation does not dissolve your debt. You and your spouse must decide who will take responsibility for any outstanding debt you shared while together. Outstanding debt includes mortgages, loans, credit cards, or lines of credit.
Usually, you will not be responsible for any debt your spouse accumulated before marriage. You can avoid confusion by referring to your Prenuptial Agreement if you have one.  This agreement will specify your separate debts, property, or assets prior to marriage.