I’ve set the date

Yesterday my 15 year old Ratterrier Taco began Coughing a lot which is not out of the usual as he has fluid in his lungs caused by heart disease and has a collapsed trachea. I took him to be checked out this morning and his trachea is almost completely closed. His Dr. upped his medication to keep him comfortable for the weekend and he will be put to sleep Monday evening. I’m now focused on spending this weekend with my best friend since I was 3 and making plans for after his passing. My question is, what now? I’ve never been without him and can not sleep peacefully without him beside me. I can’t imagine a world without him and now that’s about to be my reality.