I just typed up 4000 characters worth the text for this and it got erased so forgive me if this is a tad more short and sweet.
My name’s John and my 15 year old girlfriend of 13 month’s name is Kara. Shes suffered from an eating disorder for the duration of our relationship and it’s grown to a state of Bulimia recently. Here’s the quick rundown of her eating disorder’s history and progression
She was discontent with her weight around last july and began dieting. By october she’d lost 20 pounds and was checked into a rehabilitation center by her mother. 3 months later she emerged with all the tools she needed to stabilize her mental state and physical weight, however shortly after she began to fall off the edge. Her mom had been taking her to routinely weigh-ins and therapy. As her weight declined she began to stuff weights in her clothes to appear as if she was up to the 110 pounds her mom thought she was. This went on until she slipped up around 4 months ago when her mom surprised her. She weighed in at 98 pounds and her mom went on to force feed/control her diet with a constant flow of foods high in fat. As a result of this she developed purging behaviors to compensate for the bingeing. As her mom backed off with the force feeding the behaviors stayed with her. Her mom saw her eat and assumed everything was alright up until this weekend. Her mom noticed she was looking a little underweight and weighed her to find she was still at 98 pounds. The resulting arguments and threats to send her back to rehab left Kara traumatized. She came to me and a mutual friend in search of help, willing to do whatever she could to put on weight and end her bingeing and regurgitating without resorting to being sent back to rehab by her mom. We sat down with her mom and convinced her to give us two weeks to get her into a better state mentally and physically before she jumps to rash actions. This seemed to give a sense of optimism that lasted until about 5 hours ago. We’d planned on keeping her on a high protein diet and keeping in touch with her constantly to make sure she wouldn't relapse.
The friend was intent on taking her to his house to make her dinner but instead had a change of plans. He brought her with him to his friends house where he had to help him with his a wiring problem. He wasnt able to bring her back to around 930 which she told him was too late for her to eat. When she got home she ate and went to sleep, waking up an hour later to binge and purge, angry at him and herself for doing it. Now its 130 at night and shes lost faith in her best friend who was previously a huge source of support and in herself. She’s driven to the point of suicidal thoughts by her disease and on top of everything her grandma’s nurse called and told the family she had till the end of the year to live.
She’s in desperate need of someway to get back on the right track and this is really her and my last resort. A few questions i really need answered-

-how do i control her/rationalize with her and how does she help to calm herself down when shes having an episode (forgive my lack of appropriate terminology but im
referring to the state of mind she gets in after she’s triggered)

-how can she prevent triggers
-how can she stabilize her diet without causing all of her weight to go straight to her stomach
-how can she regain faith and keep optimistic after failing herself over and over again?

Any help at all is IMMENSELY appreciated. She’s such a smart and beautiful girl and its such a shame that this has gotten the best of her. I really dont know how much time she has left/how realistic her suicidal thoughts are. Her eating disorder has reached a climax and shes in desperate need of help.