I am sorry OP. It is always difficult.
Did you live together? If so can you move some of the furniture around, just to make your lounge/bedroom look a little bit different.
Try as much as you can to break the routine that you had. Take a different route to work, shop on Tuesday instead of Friday for e.g., order something different from a completely different take away.
Cry, scream and shout. It is okay. You do not have to be brave and try keep all those emotions in.
Do not sit around with nothing to do right now. Go out and have a walk. Go to the shop and browse around instead of an online delivery. Just be doing something. Maybe even do a few squats. Change your hair, can you colour it or change the style a bit.
These are essentially distraction tactics. Just to distract your mind from your old habits and routines.
It takes time though. And there is no set time for this, so don't set yourself a time and say for eg, I will be over him in 3 months from now. All you are doing now is taking each day at a time.
Keep posting if it helps you. Lots of people here have been where you are now, and come out the other side all okay. You will, but it takes some time and plenty people here will help to distract you x