i agree w/ ICS 110% - look at even this forum - something said like 2wks ago is already gone and new topics are at hand every day. sure - if you want to go through archive and archive - but why? - rarely does anyone else.
the problem (along w/ self-esteem issues) - is your guilt is making you believe that people actually care about blogs or twitter or FB or myspace (geez - i haven't gone on my acct. since who knows when) - - - FYI - unless you are like the POTUS or a kardasian (sp) - no one remembers nothing from that time ago. unless you were publishing data/evidence that was backed by actual hard copy that was false and that data/evidence was cited by others - then everyone knows (or i hope everyone knows) that what's put on the internet should all be taken w/ a huge dose of salt and then some.
if you actually have online friends you want to keep - then keep those and the related personalities if necessary. but the rest of them - just ignore them, in time they'll all go away - or if you want to spend your time actually going about and 'deleting' them take the time - but that is sort of a non-sequiter since nothing can actually be 'deleted' from the internet.
it also sounds like you may have a OCD problem, which you may face or not, your call. i'm sure most of your real life friends actually know this, whether you know that or not. - - - of course the most obvious solution is to turn off your phone and your internet connection for a year - and you'd be surprised - nothing happened!