It sounds like you're eating simply because he's leaving. If it were me, I'd write write write all about that. Get it ALL out--anger, frustration, loneliness, abandonment, tireness, everything. Over and over and over, if I had to. As you say you're NOT hungry, and that ISN'T why you're eating. The first thing to do is STOP eating. The second thing to do is figure out why you're eating. From there, you address it. Better the enemy you know, right?
Come here and write, if you want. We'll listen.