Thank you for having the courage to ask this question. I think it is important for you to know that the struggle to find a balance and seek answers is, perhaps, the most important ingredient in finding some answers and some peace.
There are several features you describe, such as the rapid change in mood, the separation triggering a suicide attempt, the fear of losing someone to someone else, ending medication when you feel better, and a sustained elevated mood with the return of an eating disorder, that suggest a more thorough evaluation of your situation is in order. For me, you saying “there are two competing parts of my brain” is the most telling. Classic symptoms of depressive mood alone rarely have this — and it is something that will be believed if you express it.
I highly recommend an evaluation by a psychiatrist who can make some decisions with you about the best path going forward. Let him or her know about all the things you’ve mentioned hear. This will be the best way you can help them help you.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral