Don't worry about it. For the most part you can't be bound to keep things secret in this way. Most lawyers and para-legals wouldn't know a duty of confidence if it rose up and bit them on the bum.
You can't impose a unilateral - one-sided - duty of confidentiality on someone. 'In confidence' is something that lawyers and DCA's put on the top of their letters without thinking or without understanding what they are doing.
Normally a duty of confidentiality only comes about as a result of a specific agreement to keep a secret.
Unfortunately most ordinary people don't understand confidentiality either, and they go along with it. If you agree to accept a payment on conditions of confidentiality, then you are bound by it - but why grant confidentiality in the first place. Refuse to accept any secret payments. Normally speaking, a requirement of confidentiality is no more than a try-on.
Secrets learned by eavesdropping may be protected by confidentiality without agreement.
Wrong-doings can not be protected by confidentiality, regardless of agreement.