either you lent him your credit card, or you let him spend it by default.
unless he stole your card and swiped it without your knowledge, on this premise, if the other party only signed (that is, your credit card has no password), the consumption is the responsibility of the bank, and you don't need to bear it. If the other party is spending by password (that is, your card has a password), this is your poor custody, and you will be responsible for at least 5%.