Have a friend that ended a seven year relationship (with a one year engagement). $10k ring, trip to Paris, all that. He was, obviously, as devastated as you sound. Absolutely convinced that he'd never be happy again.
He's now in a two year relationship with a girl that's made him happier than he ever was at any point in those prior seven. The change is dramatic and drastic. Frankly, it's a bit unbearable! :D
You will pull through. If he could do it, you can. It wasn't quick, it wasn't easy. There were good days and terrible ones. But he fucking dragged his ass out of that pit, and he's better for it. You will too.