husbsnd wants divorce and has been buying girlfriend presents on credit card in his name. Will I have to help pay that debit off when we divorce?

Generally, debts incurred after the date of marriage, to the date of separation, are marital.  An exception would be debts incurred soely for the benefit of one spouse.  If you are separated, they would not be marital debt, and in any event, they are clealry incurred by him alone.  So, as long as the cards are in his name, only, you should be fine.