My condolences on your loss. As a parent there is little I can say and as a lawyer there is little I can add except that it is unlikely you also will incur financial loss on top of the great loss you have already suffered.
Unless you expressly or impliedly signed for or otherwise guaranteed the obligations of your son, you have no financial responsibility for the obligations.
However, to the extent that his estate had any assets of value, the estate would have to be used to repay his creditors BEFORE his assets could be distributed to his heirs at law (his children, if any, or his spouse, if any, or his parents).
If there are any items that he owned, make a careful record of them just in case a creditor comes around and asks you to pay -- you will want to show you did not take the value and leave them with the debt.
