You try to "brush over it", you "can't stop it", asking how do you "handle it", you can't "control it", etc. Did you even read what I wrote? I'm gonna be blunt...my advice is about as good as it's gonna get (so reread if necessary), there is no quick fix so you can go ahead and stop searching.
Answering to SPQR...it's normal, read any decent book on memory/memorization and/or neural networks to understand why. If you want to move on then read my first post; if you want to stop thinking about her as much (and no they're not the same thing), then put simply...start investing (emotionally, physically, financially, time and/or effort) heavily in new, preferably enjoyable, and in overlapping 'things' in anyway related to and/or associated with one or more of your current problem trigger/anchor points. Beyond that it gets a bit complicated. In all honestly though, if you're not hung up on her then who cares, memories aren't bad unless you make them such.