I can so relate. Have you got any hobbies? I like going to the cinema, swimming, reading and cooking. Do something you like. It doesn't need to cost you a lot. Just do something for you even for 15 minutes as it'll take your mind of thing for a while and you'll feel better
Trust me I have been there.
I have a hobby that takes up an entire room in the house. I scrapbook photos and make cards, but since H left I have not had the slightest inclination to do it. I've even tried to force myself but it is like nothing is any good without him in my life. I feel all consumed by H, what he's doing and wishing he still loved me.