You have 2 normal issues – you can’t cope with the split and your imagination is running wild.
You have to go through the mental pain, but accept it and work around it so you dont let it dominate you like it is. Imagination works both ways – if she thinks you are having a great time, she will be thinking the same and may come back. Cut out the I miss you bit and instead tell her of the great stuff you have going on, would she like to join in.
You have a week off work – this could be best or worst. Sit at home moping or use the time to make yourself get out and things that you wont feel like doing but will bring up your endorphins, make you feel hopeful about life and happier about things generally
Either way, if you get out there you will either get here back or be in a much better place to find someone else.