Don't ever go online without a firewall and don't let him through it.
Well, since you have to add him again, do the best you can to protect yourself.<br />
Make sure that you have installed anti-virus software. Then change your IP.<br />
I had the same problem a long time ago, outside of not adding them period & making sure you use a firewall, Do not accept any files he might send you.. There are lots of ways to crack into one's pc via 1 on 1 file sharing. What happened to me was my "cyber stalker" sent me a rather large music file, at this time I had no firewall. <br />
Once someone hacks through your messenger, they can then acquire your ip address. Once they have that, they can use any of the remote admin. tools to preform netbios hacking. Thankfully I found the little skagg lurking on my laptop the next day when i did my daily scans. Needless to say him and I don't speak anymore, and I now don a firewall.. ..lol
what do you mean you have to add him again ?
I find pipe bombs to be effective.
The easiest way is not to add him - period. Don't let someone you can't trust into your network. You couldn't trust him then - what's changed? The best predictor of future behaviour is past behaviour.<br />
And take a course or two in computer security. Some of the best geeks are girls! It'll do a lot for your confidence too.