How do you get over a break up fast?

So yeah my boyfriend broke up with me and boy am I hurt. I haven’t really slept much, or eaten in the past 3 to 4 days. I have been crying non stop. Even crying at work. I lay in bed all the time and I tried to force myself to go for a walk but just turned around right away because I started to cry.
I ate some food last night but then started to cry so hard I threw it up. I am feeling so upset and hurt because he promised he wasn’t going to leave me and now he said he thought he could handle this but now he can’t.
All I’ve felt all week was sadness and numbness and I want it to go away. I want to be happy but I can’t. I feel like I screwed everything up.