That is the vicious cycle, isn't it?
Recovery, weight gain, relapse. It is hard to keep a good balance. I am struggling with this as well, lately. I went from a low weight to..well, a lot more. I am watched a lot, however. My fiance seems to have a sixth sense for when I am falling in to the cycle, and while he doesn't say anything, he hovers and makes it difficult to do so. Strangely, this does help?

One thing that did help me was the book "Brain over binge". She mentions in it something along the line of "What happens if you do not binge?" "What happens if you don't eat that?" She goes on to say that it is like a roller coaster, it will feel uncomfortable for a little while, but thats it. Nothing will happen if you do not eat that bad food. This 'nothing' is a lot better than the purge, right?
I have to keep telling myself this.
I am teetering on binging and being unable to purge so I end up purging through long hours at the gym or hard restrictive days.
This relapse will be the third time since high school, so I feel you.