Genuinly smth very VERY serious

Idk if this fits here or not as it all happened in this server mostly but its slso not rlly related to it, but heres what happened: A user, of whom I will not say the name of so i don't get hacked, has been hating on everything I made and, im assuming, got banned for saying some pretty bad things towards me, then just about 4 minutes later I got a notification, I was mentioned in a post by him. Guess what it was? He leaked my reddit password and my roblox password and username too. Please, please tell me what to do about this, this is way WAY too serious to be going on over a kids game, like I thought he just wanted to ragebait people so I played along and then he actually follows through with his threat.