can you be sued for something that happened over 10 years ago?

That depends on what type of claim is being asserted.  Technically  you can be sued for anything at any time, but in most cases can succeed on a motion to dismiss because the statute of limitations for most claims is less than ten years.  There are also circumstances which can extend a statute of limitations, such as the plaintiff's minority, the defendant's absence from the jurisdiction for a period of time, defendants' concealment of the facts giving rise to the claim (separate and apart from the claim itself), etc.