Happened to me several years ago and it's the hardest thing I've ever been through (and unfortunately I've been through a lot). You're all doing great and you will get through this.
Mine was a long term relationship, living together, heading towards marriage, and then one day he just dumped me completely out of the blue.
The shock was horrific. The sheer pain, the constant crying, not being able to see a future. The total confusion, wondering how he could change so suddenly. He was also my work colleague and that was very tough.
I was extremely low for the first few weeks and then had very gradual improvements after that. Overall I'd say it took about 4 months to get over him, and another 4 months to adjust to my new life. I got a cat which really helped, then had a fling which was fun.
My ex was a crap partner, emotionally stunted, immature and a total commitment phobe. I just didn't know any better at the time. I'm now about to marry the most amazing man, who is 100000% better for me than my pathetic ex. He's loving, kind, affectionate and not afraid to show it. We are so much better suited.
Saw the ex walking down the street a few weeks ago with a woman. Time has not been kind to him, and I just felt sorry for his new partner having to put up with his shit.
It's does get better. And whatever you do, don't message him. Block his number right now and you can always undo it when you're in a better state of mind.