The fact that you have not killed yourself is indication to me that there's doubt in your mind that you really are suicidal. Most who get the urge to kill themselves just go and do it, many don't leave notes or messages as they just get on with it. So that is a good sign. Because while there is doubt in your mind, it means there is a chance you can save this. When you think of it, killing yourself won't change anything. If you're unhappy about your size, for example, if you kill yourself, then you die big. You can't change it then. But when alive, you have the ability to change things, and turn yourself into anything you want to be.
Diet is a weird word, it strikes fear into so many people. And most of them are rubbish, they don't work. People stress too much on size, and if you want to change, you can. You just need the right support, the right advice and the right mental attitude. You can't and won't change overnight. And it's a longterm process. Your current mental state will effect how you eat as well, as depression makes your size change.
My advice, if you're feeling this way, is talk to your Dr about it. He/she can maybe help you with some advice on dealing with your depression or mental state first. You might need some short term help with medication. They can also refer you to a dietitian, who can help you work out a good eating plan for you, and also advise on exercise. You can't lose weight just through eating alone, it has to be a combination of eating and exercise. And the exercise can be gradual, you know, a walk for 30 minutes is sometimes better than going to the gym, and doing a whole bunch of exercise that's not right for you.
Don't give up, if you want to change, you can. You probably just need a little help to get started, and if you ask for it, I am sure your Dr will help you get going.
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The only good thing about breaking up
Is the making up we do after