Weekdays can carry you. Work starts, messages arrive, people need things. Then Friday night lands and the time that used to belong to the relationship suddenly has no plan.
Put three anchors in the weekend before it starts.
One reason to leave the house. One person you will have contact with. One thing you can do alone without it feeling like waiting.
That could be the gym Saturday morning, coffee with somebody in the afternoon and a game or film at night. Nothing impressive. Just enough shape that the entire weekend is not one long emotional blank.
Make one plan that belongs to the new version of your life.
Not something designed to make your ex jealous. Something you might genuinely keep doing. A class, walk, gaming session, new café, training session or community event.
If being alone suddenly feels like the biggest problem, Single On Purpose (affiliate link) on Amazon is more relevant than another generic breakup book because it focuses on building a life that is not simply the waiting room between relationships.
Plan for the moment you want to contact them.
Do not act surprised when it happens. Decide beforehand what you will do first. Write it down. Message somebody else. Go outside. Wait 30 minutes.
A plain Moleskine notebook (affiliate link) on Amazon works well for unsent messages because there is no notification, reply box or profile one tap away from the page.

Sunday evening needs its own plan.
Sunday can be the part that catches people. The weekend is ending, the distractions are gone and another week without them suddenly feels real.
Eat properly. Get what you need ready for Monday. Keep the evening simple. If you can, arrange a call, community chat or gaming session before the loneliness gets to choose the activity for you.