mon_of_steele i recently had almost the same experience, a dream, lingering on it, finding her on facebook, etc.
you need to remind yourself why it didnt work. you mentioned she was fucked in the head, well she probably still is. dont downplay it now because you are horny or feeling nostalgic. my ex i had a dream about had a perfect ass, coy smile, loved to suck dick. then i start to rememeber the 3 am phonecalls accusing me of nonsense, her penchant for trying to create drama, her selfishness.
this too shall pass