On the second part, you should not write to other tenants. If what you said is not true, the agent would have a defmation claim against you and the damage recovery is unlimited. At least he would claim false light of invasion of privacy against you. Even if it is true, he should still have a claim against you under public disclosure of invasion of privacy.
If God forbidden that happens, you should hire a lawyer and your defense should base on your qualified privilege, that you did for the purpose of the other tenants, or benefit of your own. You need to prove that you did not abuse the privilege, such as excessive publication.