Two can play the game. He has little or no proof that you stole money from him. If he tells the truth to the cops, that he discovered the theft months ago, and continued having the relationship, they probably wont pursue the case. If you go to the police and say he forced you to have sex with him under threat of arrest, they might take action. The crime could be coercion.
More details would be necessary to properly discuss the situation. You might want to consider consulting with a local attorney. Good luck.
This answer is only for informational purposes and is not meant as legal advice.
Whether the grand larceny charge sticks depends on the evidence. I suggest you not speak with the police without a criminal defense lawyer.
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