with the emphasis of what
@John *********
told you: IF (yes: only IF!) they notice it by the next time. So the advice is, DON'T act, don't do anything, exit Thailand. Immigration at the airport won't care. Take your chances, when you re-enter, after 90 days you need to do the 90-days report by yourself on Immigration, keep fingers crossed they won't notice your flaw, but be ready to pay 2000 THB in fine if they insist