In order to help out anyone else and be available for them, not only do you have to look after yourself, but you also have to set a prime example of a good treatment. I know this is much easier said then done, but it's achievable.
While I was reading about your excessive and obsessive weight loss, your somewhat overweight body beforehand, and the two completely opposing types of comments from friends and family, it was like I was reading about myself! And now, even though I'm so relieved without the weight complex all the time, I don't feel happy. Is this what you're experiencing too? Maybe you can start taking care of yourself one step at a time, so you don't feel overwhelmed. I am now at a point where I don't want to gain any weight, but I also don't want to lose any more, 'cause I'm beginning to look weak, and that's just not me. So I decided to take vitamins every day, to SLOWLY increase my protein intake and SLOWLY cut down on exercises I do. It's scarey sometimes, but I'm also a college student with high academic goals and in order to achieve these and enjoy life in the long run, I really can't just "not care about what happens to me" and I think you should think along the same lines. Best wishes to you and let us know how you're doing!
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"When there is no enemy within, the enemies outside cannot hurt you."