I'm so sorry you are having such a rough time.
I would delete him from every angle of your life and give yourself permission to grieve over this lost relationship. Time is a great healer...I know it's been said a lot, but it is so true.
Take a few days to sulk, cry, get angry, cry some more. Get it out of you ... don't hold it all in. Once you've cried out your tears, start making some plans for yourself. Find your way back to everyday life. Make plans with friends to go out for lunch or dinner. Go for a walk on a nice evening. Go bowling, it's a great way to get out your anger on those pins! Write your feelings in a journal....free writing...anything to help get it out.
When your mind starts to wander...give yourself a little break. But get right back to the task at hand as soon as possible so that you don't loose sight of what you need to do. Most of all....don't play the "what if" game with yourself. That is not going to fix your relationship nor make you feel any better.
Just know that what you are going through is normal. Be kind to yourself and know that you won't always feel this way.....it can and will get better!
Take good care!

sabby