CW - Man, I don't think I can unfriend her. That feels like war. I can decide to be on FB less or remove my profile temporarily. I don't get on it often at all. Just happened to check it Saturday and then I wasn't look for her, her second profile just showed up in my "People You Might Know" section.
"War", hmm? Interesting. To me, it says "no" to being friends immediately after the breakup. I don't want to know if she has an amazing trip somewhere we planned to go, buys a new car, or gets a worrisome medical diagnosis. I don't want to see new BFs or GFs. My detachment is an act of self-preservation made with love and no hostility behind it. 4 of my ex's made the same choice. I didn't interpret them as hostile.
The choice of being friends vs. not being friends right after a breakup is a big one. I choose "No" for now, like those 4 ex's. I am free to re-visit in a year. I have reconnected with 2 of those 4 ex's as friends.
I agree deleting your FB account or de-activating it until you're over her are viable options. I won't do that, personally, because I use Facebook to exchange family photos (e.g., Christmas in 10mo). I suspect it'll be a long time before either of us wants to see our ex's celebrating Christmas with someone else.