Dear clueless,
I would go to your guidance councilor and ask for help, because that is a serious lie. Fixing the situation with the people who find out is going to be a challenge, come clean with them if they are close to you, sure they will be mad at first, but maybe there is another underlying reason why you decided to come up with that lie and they can help you try to get to the bottom of it. As far as people finding out to who you aren’t really close with, disregard the statements, it is no body’s business but your own.
I hope this helped at least a little bit :D