Need advice on how to proceed

So i started selling on amazon and I’m selling under a brand with multiple sellers. I sell mine at lower price and other seller is mad sending threats on a third party platform and I’m afraid he will do something underhanded to get my account in trouble with Amazon and force me to stop selling. I keep my price lowest because when our prices are even his listing is on top and not mine. Even if i report him with proof of our conversation, he can still try to sabotage my account. What do you guys recommend? The conversations in the third party platform are not me and him directly, i have a middleman doing the communication.