Im so confused and I feel like I need advice from people outside of my circle. I have an fat fetish. Im sure its common and people already know. I've been with my girlfriend for about 7 years now. When I first met her she was about 230 Ibs. Beautiful and amazing. I admitted to her that I was attracted to her bigger and as any girl would react... shocked and lost of words. I explained to her and she finally accepted it. Now 7 years later, she's almost 370 Ibs. Her doctor says that she's at a very high risk of certain diseases and that she should go through Gastric Bypass Surgery or start on an lifestyle of exercise, dieting and weight loss pills. He knows I and Isabella's situation and warns me to stop. I've been trying and trying and yet I'm still encouraging her to overeat. I think its impulsive and its something I can't handle. We've argued about my fetish a zillion and one times. And its always ended up her craving into what I want. I feel like a douche for everything and I really care about her health because I don't want to lose her. Our Relationship is overall amazing but my fetish is ruining everything.
I've gotten couple's therapy for about 6 months now (since she's been on her diet) and its just been an headache completely. We can't seem to come to any point in which we are able to live with this. All the therapist does is ask us questions and takes notes which causes us to bring up points in our relationship that we fight about. By time the session is over, we're completely upset at each other. But its also hard because if she's on the diet and I chose to eat whatever I want, I don't necessarily want to eat fruits all day long.
I just need to know what to do anymore.
I've been considering leaving her for her own good or moving out for as long as I must because if I keep involving myself with her, I don't think she will ever lose the weight.
I just need advice other than my friends, family and my therapist.
What should I do?

Well I am sure you are getting useful information from your therapist but more than likely you can't accept it. You already are aware of her health condition and you she is doing what is best for her. Maybe you should look into group therapy and maybe time space apart will help.

You need your own special help, that's just for you.

You need to worry about her health, being heavy is one thing, being seriously fat is another.