I wonder how the two of you would react if something like this would happen to you..
That's not the point; this isn't a chat room, it's a publicly available globally accessible web forum indexed by Google, and therefore we aren't just thinking of what we or you personally might or could or would do, but also who else might be reading this in the future. Furthermore, even if you did know this person's IP address it is hard to see what you could do with it, since the actual name and street address of that ISP customer is held by the ISP, and even if you knew that, taking the law into your own hands might well get you in trouble with the police, and would make you just as bad as the person you allege is "stalking" you. In fact it sounds like you want to find out their IP address so you can stalk them back. How do we know you aren't making up the stalking thing anyway? People do make up stories on forums to get people to help them do things that they shouldn't. For xxample "My kids reset the laptop password" to cover "I bought a hot laptop".
