Relationships should always be a pleasant experience, but sometimes it just does not work out that way. We tend to lose sleep, over-eat, cry and then cry some more.
Letting go is hard to grasp at times and it takes weeks and months to move past the hurt. It may even seem impossible, but the good news is, you can move on.
The first thing you need to do is make a decision to finally move past that negative relationship. Once you look back at all of the hurt from the negativity, you must realize that you are better off without the relationship anyway.
To not let go is to keep reliving the past over and over again. This is not healthy for you. There is no way to change the past, but you can change how you feel or think about it now.
Realize that sometimes these experiences are meant to be learned from and help you make room for something better in your life. There will always be someone out there that will treat you more positively.