Didn't something really similar to this happen way back on EBS? Got an elephants brain...
The fact of the matter is when you show up online, and are traceable, you need to understand that you are opening yourself up to more potential crazies. It's not justifiable behaviour but at some point you need to weigh out the risks and rewards.
Is the reward of stating your opinion on a basketball site worth it?
You are placing your statements in a public domain and it is the risk you run. Personally, I have little concern about my online identity because the effects are (hopefully) to be confined to the internet. Similar to your statements if things left that sphere I would be an unpleasant character to deal with.
Unless someone is doing something that is illegal, they are allowed to insult you all they want. While it would be nice to control these things, it can't be.
I understand you concern about personal information being shared but when you place something in a public forum, you undertake the risks that your life will further develop in a public forum and maybe in a way you don't like.