Does the Bible say that if you lie, you have to tell whoever you lied to that you did? I am wondering because I have been obsessing over something that is probably stupid to obsess over. Anyway, it was a long time ago, and I don't even know for sure if I did lie, and I am wondering if I did, if I need to tell them. But I am obsessing over whether or not I did lie and if I need to tell them. What should I do?
Either you told someone a lie or you did not. A lie is to tell someone something that you believe to be false at the time you told them. It is not a lie, for example, to tell someone that the meeting is at 3 pm, and then you later learn you had the time wrong and it really was scheduled for 2 pm.
What the Bible also says is that when you sin, you are to repent of that sin. Repentance from sin means making a complete turn around in your attitude and behavior toward sin. Paul said he "declared first to those in Damascus and in Jerusalem, and throughout all the region of Judea, and then to the Gentiles, that they should repent, turn to God, and do works befitting repentance" (Acts 26:20).
A part of the change is a desire to fix problems that you may have caused when sinning. "For godly sorrow produces repentance leading to salvation, not to be regretted; but the sorrow of the world produces death. For observe this very thing, that you sorrowed in a godly manner: What diligence it produced in you, what clearing of yourselves, what indignation, what fear, what vehement desire, what zeal, what vindication! In all things you proved yourselves to be clear in this matter" (II Corinthians 7:10-11). Zacchaeus demonstrated this when he turned to Jesus. "Look, Lord, I give half of my goods to the poor; and if I have taken anything from anyone by false accusation, I restore fourfold" (Luke 19:8). Zacchaeus declared that if he wrongfully took money from someone, he would return to that person four times what he stole. The Jewish Law only required that a thief return 20% more, but we can see Zacchaeus' zeal in wanting to change because he was willing to do more than the law required. Of course, there would be many whom Zacchaeus would not remember or not able to restore. For these, Zacchaeus declared he would take half of what he had and give it to the poor. Perhaps those he stole from would benefit, but in this manner he removed the ill-gotten profits from his own household.
Notice, though, that Zacchaeus did not say he was going to track down every person and deliver a personal apology. Many would not be available. Many would not be known. Rather Zacchaeus is letting ti be known what he is willing to do and he hopes any who harbor ill against him will contact him.
If your lie caused someone harm because of your lie, then you should make up for the harm as best you can or let the person know that you regret the harm that you might have caused by your words. From a practical viewpoint, I doubt most people can remember all the lies they told or all the people they told lies to. But you can focus on the future and become a man whom everyone knows is totally honest. That change in your behavior is "works befitting repentance."