It may not matter whether you really took anything. It only matters whether the Detective thinks you did. I suggest you at least immediately consult with an experienced criminal defense attorney and have them speak to the Detective instead of you.
Generally, when law enforcement seeks to question you about a crime they think you have committed, they already believe that you have committed the crime. While you may not have done anything, most law enforcement will take any statements you make and seek to determine how they incriminate you.
When this happens, you should seek an experienced criminal defense attorney to consult with. Pending the consultation, you should avoid discussing this matter with anyone other than your attorney.
Yes, you need a criminal defense lawyer. Do NOT speak to the police, or a detective without an attorney present. This detective has decided that you are already guilty and it's unlikely anything you say will change his mind. That is where a defense lawyer can help. Speak with a local attorney who can guide you through this process and help you decide how to proceed.
Detectives make mistakes all the time. Innocent people are accused, arrested, and in Texas regularly convicted for crimes they did not commit. Don't let that happen to you.
You should hire a lawyer to talk to the detective if that person believes that is a good idea. A good cop can twist your word and put words in your mouth. You should not have any further contact with the detective. It does not sound like he is on a fact seeking mission but on a hunt for prosecution. Even innocent persons can be caught up in a tangled mess in such situations.