awful so sorry for you. Do not really have any expert advice, but wanted to say that you need to slow down, give yourself time to take it all in, and most of all to look after yourself.
You are going through an awful experience, but you will get over it, and will look back at this as a blip, not the end of the world. But obviously that will take time.
Yes it would be lovely if you could fast forward time, but you know you can't. So what you need to do is take each day at a time (cliche I know, but it works). Give yourself a goal of getting through the next 24 hours - then give yourself a big pat on the back when you do.
And most importantly, you need a good support network around you. Don't know if you've confided in any of your friends of family in RL, as before you were obviously trying to work it out, but as you now know this is for real, you need to talk to people who will be able to support you and get you through this. Do you have good relations with your family & some friends you can talk to? I know it will be hard but you will start to feel better even just from 'offloading' some of this.
I know there is so much for you to sort out, legally etc, but for the next few days I think the most important thing is for you to look after your emotional health.
There is also the issue of him saying he's leaving 'asap'. Well if he's definitely going, I think you need to start getting back some control and tell him that he has to go now. Doesn't matter if he's not sorted out anything permanent yet; he can go to his parents or friend or whatever just for now. Because you cannot start to heal yourself while he is still there.
Am thinking of you - and we will help you through this x