Hi Staren.
I'm like you. My first reaction in most instances is to engage the other person in discussion and to be polite about it. And just like you, it often creates more trouble than good. It's been a while since I've experienced anything as bad as what just happened to you though!
Once I was at a spawn and a guy was kill stealing from me using arrow. I called a GM. Noxide came and told the guy to stop doing it. The guy said ok, but started doing it once Noxide left. He got warned again, and he agreed to stop. And he started doing it again as soon as Noxide left! So he had his character moved far, far away. He then made a nasty petition about me. He then signed on with three different characters and made three more petitions about me. Nice, eh?
IRC isn't much help because there's no guarantee that a GM will be around. They're just volounteers. All you can really do is /report people and make petitions about them, and use your /ignore list as well. Even if you do get the attention of a GM, it usually takes way more time than it's worth to explain everything. The GM might not see things your way anyway, and the jerk might just make a new character or stop playing so it doesn't even accomplish anything. Things can be pretty extreme sometimes. I once alerted a GM to something some people were doing to me. The GM I ended up with said that they werent' doing anything wrong and he closed the petition. I /reported them, and the very first person who looked at the /reports decided to ban the guilty party. That's how extreme things can get. One GM will look at something and dismiss it, while another GM will look at something and end up banning people.
Adding people to your /ignore list doesn't really help because they could be saying things to other people or annoying you in other ways.
I'm not sure where I was going with that. Basically, crap happens and there isn't really any way to avoid it. All you can do is try to not let it affect you too much.