First of all, relax. You have nothing much to worry about.
If someone was badmouthing you and after getting banned threatens to "hack" you then judging from his actions and behavior it is very likely that he is just some kid trying to look like a bad ass, even though he is a complete noob who doesn't know anything about "hacking" (or what ever you call it).
Now, if he did "hack" you, then it is already too late, as he probably captured all your passwords and placed all kinds of backdoors to get access whenever he wants to. He would have sent fraudulent emails from your account to all your contacts asking them to transfer a little amount of cash to help "you" out in an "emergency". He might be even watching you right now through your webcam.
Have a nice day!
P.S. Oh, and I see this is your first post so welcome to EZ. Room 32B is upstairs to the left (I have learned the hard way). Dr. m0rph will make this issue the last thing you worry about.
Edit: if you are still paranoid, then the quick and easy way is to just reinstall the router firmware and your operating systems to get rid of all the malware, backdoors and other junk that might have gotten into there.
This made me cry quite a bit.
"all kinds of backdoors"
Personally, disabling HTML access to your router will prevent a major weakness in it. (that goes for everyone)