If there is a criminal complaint against you, you should have received a summons to appear in court. You could also call the local court. Do not talk to the police.
You can find out if there is an open criminal case from the clerk's office at the court house. You can call or go there personally. They are busy, so it might be best to do this after the morning rush.
As for the open investigation, that's more difficult. You might be able to find out if anyone has filed a complaint with the police department, but the best advice is for you to not talk to the police.
This answer does not create a privileged attorney-client relationship. This is not intended to be legal advice. Today, more than ever, people should not act in a situation that affects their rights without seeking professional legal counsel. The information contained in this answer may no longer be current or complete. The law changes on an almost daily basis.