Do not let it go a day further. Do you have any documentation of his offer to pay you for the training you did? Anything in writing at all? By ignoring it, you have only inadvertently encouraged the bad behavior. Have there ever been any witnesses to this? If not, you are in the unfortunate position of a "he said, she said" case, which is hard for the law to do anything about. Bring someone you trust with you the very next time you go to the barn, doesn't matter who. Speak to him in front of that person, and let him no no further touching of any kind will be permitted, and no further comments about your body. Explain you will be recording any future interactions with him, just in case. (Many phones or other small electronic devices can do this.)
That should hopefully buy you enough time to get your horses to a safer place for everyone concerned.
Is there anyone in local law enforcement that you know?