@ThinksTwice
This is how I would go about it: It's very much a belt and braces method for a good energetic clean.
Get rid of anything belonging to your ex
Give the house a good clean and tidy ( negative stuff clings to dirt and disorder)
Work methodically from top to bottom
For each room open all drawers and cupboard door as you start to clear it. ( leave the negative energy nowhere to hide)
Shift the energy using either noise or smoke. I use a drum but a saucepan and a wooden spoon does the job. Make sure you get into all the corners, under tables, inside cupboards etc etc. If you choose to use smoke, white sage smudge sticks are popular. I use bunches of bramble myself.
As you finish each room sprinkle a little blessed salt water along the windowsills and an other entry places. Close the door behind you and seal that with the water too.
Wor methodically through the hose until you reach the hallway. Push all the negative energy through the door to the outside, close the door and seal it with the water.
Now you need to refill the space with something nice. Your favourite music, incense, maybe some dancing singing, cook your favourite meal - anything that gives you pleasure. You may want to sprinkle some peace water or florida water around ( plenty of recipes on the internet). That is entirely optional but they help to keep the place clean and smell lovely!
Good luck!