When you come across people trying to run you down professionally, the best advice is to keep your head up. If they're being mean-spirited to get a rise out of you, remove yourself from the situation. If they display childish ways accompanied by an unsavory attitude, it's time to leave the business relationship. If you're under a contract, that could get messy. For your sake and legal purposes stick to your part of the contract until there's a resolution.
A friend of mine who writes screenplays and has been in this business for over fifteen years became the victim of a scam. He met the person through networking, completed all of his research and wrote the script. Eventually he ended up going to court.
As for myself, I've been in the entertainment business of acting and writing since 2004 and I've experienced both the good and the bad. I'll tell you the good first and save the bad for another time.
When I took up acting I was blessed to have an awesome talent agent, Peter DeAnello, who played by the rules. He didn't charge a fee and worked with us to improve our craft. On the day that Peter signed me, he said, " 'You will have to develop a thick skin. Learn to accept criticism.' "
That same advice applies to us as writers. We all watched what happened when an author recoiled at a bad review and lashed out with rude comments. If you’re not careful that kind of behavior may come back to haunt you.
Our reputation plays an important role, especially, when trying to land a literary agent. I'm still honing my craft and learning the do’s and don'ts of this industry. I recently learned of the percentage of people who WILL NOT get a literary agent. Yikes, I thought.
So when I renew my subscription every year with Writer's Digest, order books or scroll the twitter and facebook feeds, I label it as work. Read, update, and learn your craft, so if you happen to come across that "unhealthy person," hopefully you will have enough information to stand on your own.
