I find that as time passes and we get farther from the situation we tend to push aside the horrible things that occurred that made us break up with them. I would be so mad when I broke up with someone and then a couple months later when I was removed from the situation I would suddenly think "It wasn't that bad.." and then I would suddenly remember all the good times we had. It is easier to remember the good times when you aren't in the middle of a toxic relationship.
Keep moving forward and reminding yourself of the reasons you left when you start really missing her. That has always helped me.