It’s probably hard to do right now, but think of it as a new begining, and a chance to make all the changes in your life you’ve always wanted to, but have been too settled to actually do. Take some time off work, and travel. Buy that new bike you were scared she’d go apesh!t over.
On a more practical note, if you have joint finances, go to the bank and split them now. Do some proper budgeting, and work out if you really can afford to stay there, and whether you would need to cut back on certain areas if you did. Prioritise things, and do what’s most important for you first.
Before any of that though, talk to her, calmly, and find out why she’s decided to leave you. Chances are you’re not going to be able to change her mind, so just treat it as some sort of closure. If you don’t find out why, it’ll always nag at you.
If you want something to help you see the positive side, a mate of mine was divorced by his wife of 5 years, 2 years ago. He was devastated, and to be honest, we were all worried that he was going to top himself, he was that low. She did her best to completely shaft him in the divorce, and to be honest, she’s still trying to do it now, despite the fact she’s shacked up with the rich doctor she left him for. Doesn’t sound like a happy story does it? Well, he’s now happier than he’s evere been. He does what he likes, goes out when he likes, sleeps with whoever he likes, goes on holiday when he likes, and nobody tells him not to. All his friends have been very supportive, and he’s come back from being as low as I’ve ever seen anyone get, to being one of the most content people you’ll ever meet.
All it takes is a bit of time.