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I am sorry to learn of this situation, it is certainly unethical, whether or not it is illegal (something you would have a legal claim over) would be based on whether or not the agent represented you, or the other party.
If the agent represented you, they are breaching their fiduciary duty, breaching their contract with you, and liable for professional misconduct (negligence).
If the agent represents the other party to the transaction (for example, if you were the buyer, and the agent represents the seller), the conduct would certainly be unethical, but it would be less likely to be actionable. You could consider a claim for "tortious interference with economic advantage" or some similar claim, but this would be much more tenuous and you would have to consider whether or not it is worth investing the time and resources (money) into suing the realtor when the claim is relatively weak (not because the behavior is unacceptable, but because there is a lack of "privity" in your relationship with the defendant).
You can report the realtor's behavior to the state board regardless as to whether they represent you or the other party. The state board is going to be able to investigate this unethical behavior and take administrative action if they deem appropriate. They will not be able to get you any compensation (that is not the board's function) but they can take disciplinary action against the realtor.