Don't go there. Leave it be. Let sleeping dogs lie.
One should not attempt to friend one's ex on Facebook no matter how nostalgic (i.e. pathetic) one is feeling. Neither should one attempt to Facebook one's ex in order to gloat about your current life (it's really not a healthy impulse and it makes it seem like you're not actually happy with whatever it is you're gloating about). One should particularly not attempt such things if the last meaningful communication one had with one's ex was her palm connecting with one's face because one was lying to her, lying by omission to her and sleeping with her roommate.
Chances are, if she hasn't had any contact with one in the past eight years then she doesn't want to make contact now.
Now, to stop talking obliquely about myself, I give you NPR. And an interesting article about the digital "drive by" -- once upon a time people would roll down their ex's street to maybe catch a glimpse of the ex and/or just think about how the ex was doing. Now people "drive by" their ex's facebook page to get a glimpse of what's changed there. I suppose this makes more sense if you and your ex were facebook friends while you were actually dating. However, if you were the kind of guy who referred to social networking software as the pretentious drivel of the masses, and swore up and down that you'd never pander to such an innane level (to which she rolled rolled her eyes when you were dating), then this does not make sense. She will probably snicker when she finds out that you're "pandering" and attempting to facebook her.
Which brings me to the interesting question of whether or not to "unfriend" one's ex. Thoughts? Comments? I've never "unfriended" one. Do thoughts of the digital drive by creep you out? Do you drive by yourself? Do you have different feelings about different exes, for example, those you didn't slap as part of the break up process?