I know how you feel. I broke up with my fiance just after Christmas. We hadn't set a date and he said he didn't believe I ever would - which was codswallop, I hadn't been putting it off, I just had my mum's health to think about, and basically he got tired of playing second fiddle.
Not going to lie... I was utterly heartbroken at the time. I spent most of the first four months of this year crying non-stop and trying desperately to think of ways to fix things. And, yes, there was an initial urge in the immediate aftermath of the break-up to go raid my nearest Thornton's and bury the agony in chocolate. To be truthful I think the only reason I didn't do that is because I just didn't have the emotional energy to expend on anything, even chocolate. I finally found a situation where food was absolutely bloody useless! I know it sounds strange, but I can look back on that as an ultimate positive. Something in me broke, and it needed breaking. I suppose there was also a lot of anger there below the surface - bit of a subconscious thought 'this man has been unfair to me, and I'm not going to let him sabotage my healthy eating as well as breaking my damn heart!' The anger helped when I let myself feel it.
I really don't have any wise words - all I can say is that I know just how much it hurts, especially in the early days. Everything is just black. I remember not being able to go anywhere without being reminded of him and without feeling as if I'd somehow screwed up any chance of happiness in life. At the time a friend's mother gave me a bit of homespun philosophy - she said "what's for you won't go by you." What's for you won't go by you. When I was able to think clearly again (a long time later!) I realised just how right she was. If he's meant for you, he won't leave you. If he leaves you, he wasn't meant for you and you're better off in the long run.
I know it's a cliche, but the only thing that helps in any way is time. I remember everyone telling me this and I remember wanting to thump them all... but it's true. If you can just get through the worst days, there'll be a morning when you wake up and he isn't your first thought. Then another morning when you actually do feel like laughing about something. You'll move into the numb stage, but after that you *will* come alive again. And you genuinely won't give a toss about him.
The irony is that when you reach this state of ambivalence, he'll probably sense it and approach you with subtle overtures regarding 'getting together.' That's what happened to me. The joke is that if he'd approached me on any day throughout January to May, I'd most likely have dissolved in a pathetically thankful pool of goo at his feet. But by the time he'd sorted out his rubbish I just didn't care anymore. No grief, no anger, just very placid neutrality. I still find it hard to believe that the hurt finally ended - but it did! And I really really hope the process is as speedy as it can be for you.
Regarding eating - if you genuinely don't feel like eating much (totally understandable) then you can't force yourself. But a break-up like that is a hell of a shock to the system and I think you really do need to take care of yourself right now. I ended up with pneumonia... just got so run down and didn't pay attention to getting the food I needed in the cold months. Please don't let yourself get ill - if it helps at all, let yourself feel angry, you're entitled to! What your ex was saying is psychobabbling horsecrap. He wants his cake without commitment and he jerked you around. Don't let him screw up your health and your weight loss, too!
Look after yourself, try to get as much rest as you can and if at all possible try to keep to a healthy balanced diet, giving yourself the odd treat if you fancy it. You've had a big shock and your body and mind need a lot of kindness and patience and gentleness right now.
