Any statements made in writing could end up being admitted as evidence. Since OP might have to prove that what they stated was factual or that they had reason to believe it was factual, they should exercise utmost caution in their correspondence. What is beneficial and what is not is almost impossible to evaluate for a "non-lawyer". People are often naive when it comes to the legal process and end up dumbfounded when the opposing party twists their every word.
Amendment to my original comment: It just crossed my mind that the federal law against unfair competition (UWG) could also be applicable.
Amendment to my original comment: It just crossed my mind that the federal law against unfair competition (UWG) could also be applicable.