Stbx and credit card debt

My mom tells me that if my stbx (we’ve been separated 7 months) incurs a lot of debt on his credit card, which is in his name only, that I am still liable for half of the debt because we are legally married. Is this true? I thought that once you separated, your debt and income was 100% separate even if you don’t have a separation agreement.

You are correct each party is responsible for debts in their own name incurred after the date of separation.