It's awful when we lose someone we care about so deeply, and it's like a bereavement when it's all suddenly over.

I do think a therapist would be of great help to you and I think it's important to make the time. And I would work on the issue why this man was so important to you? You sound like you're in love with him, or the idea of him. A great friend is wonderful but your reaction to this is very very strong. Too strong. To feel crushed, not sleep, not eat... this is not normal. To feel sadness and even anger is normal, but not crushed. I do think when you find out the root of this reaction, then you will find it easier to heal.
Sorry if I sounded harsh, that's not what I wanted to do, as you're hurting. But I do think a therapist is the thing for you because I think you have some issues underlining this and your reaction is about other things too.

Hugs to you.