Unfortunately in the 'Real World' the best way to deal with bullies or trolls is to ignore them. These people are looking to provoke a reaction or confrontation so denying them that satisfaction is always best. You do need to grow a 'thick skin' and it's certainly not easy when someone is screaming abuse at you (been there, done that) but the law will most definitely not be on your side if you use violence.
TL: DR ignore bullies.