Legal Question in Family Law in California

Did you really go through a full blown legal separation, which is 99.9% the same as a full divorce case? From your question I doubt it. If you did, then the assets and debts should have been divided and you should not be responsible for any debts incurred after separation and only secondarily liable for debts incurred before separation that were allocated to her. If you have not, in fact, actually done a full legal separation case, then it gets much more complicated and you will need to go over the details with an experienced Family Law attorney in person.