Okay this is definately easier said than done, but i went through the same thing a while ago, and these things worked for me-
You should find SOMEONE you can truly talk to, a councilor is good, but a close friend, boyfriend, or family member would most likely be more helpful
You may want to begin picturing yourself (after you purge) as a shell of who you used to be, wrinkled up, shriveled, and weak, instead of the "ideal" thinness
Also, if you have told someone about what you are going through, and you really trust and love that person, and know the feeling is mutual, think of how horribly sad and dissapointed they would feel if you continue to do this to yourself
Another good trick is to try eating smaller, more healthy and satisfying meals, to keep you fuller and stop you from binging or feeling gross when you eat alot
I hope this helps, and i'm really sorry you are going through this, but you can make it out^_^