Most Helpful Guy
When we break up with someone, particularly when we knew for a fact that a lot of it was shitty, we tend to romanticise the experience in our memories. We remember the good more than the bad. It doesn't hurt to remember the bad sometimes and to remember why it didn't work out. Consider that to be a rationality check.
My general advice is that there is a fixed period of time where you can sit around and mope and feel sad, listen to sad songs and generally grieve. It has to be fixed though. One or two weeks is about as much as I would recommend. After that time you need to start dragging yourself back to life, even if you don't feel like it. It's important to be active and to stop wallowing. You need to fill those gaps in your day that the person has left behind, because every gap is a reminder. When you get to the stage that your day is no longer punctuated by a space where it feels like he should be then he won't come into your mind so much. Try to see friends, try to have fun. Once your grieving break is over don't keep loads of memories of him around, throw them away or hide them away. When you have thoughts of him then physically force yourself to think about something else. Emotional voices should be countered rather than allowed to run riot.
Most Helpful Girl
spend time with your friends. go see a movie. read a book. go to a party or the club. literally anything. it's normal to miss the relationship because you were used to being with him. and if you find yourself pulling back just keep reminding yourself of the reasons you broke with him.