If sorry you feel this way!
i have that same problem i get attached to people really quickly, and i always beat myself up about it becasue i know i stand "no chance" The only thing i could suggest is that you keep your mind busy when your out with guys or around guys, i feel like i need someone and it's reallly getting me down, c'mon your stronger than this you've proved it by posting here, i'm pround of you for getting help
It will get better, if you EVER need anything please feel free to
PM me.
I hope you feel better very soon!