I think having one "free day" per week and still losing is fr from the end of the world
What's happening to you once each week sounds like a free day- rather than a full-blown binge... Which, if you used to really binge- is a hinge accomplishment, do congratulations!
As far as it being unhealthy- I don't thiink it sounds too bad, except for the fact that its "all you think about"... That can get in the way of life- but I think a lot of us (especially binge eaters) who eat at a calorie deficit start to feel this way sometimes. For me, being too focused on food leads to a mega-binge, so I try to stay busy with other things and try to set goals other than food/weight related things... That's what usually helps me.
I'm sorry you're feeling this way and want to make sure you know that you aren't alone! Good luck!