Yep, it's gonna sting. But it will give her a chance to be alone with her thoughts. Make sure you separate on a good note, that will be the last impression she has of you.
When my WAW left, the next day she had to come get some things. I happily helped her pack her car (I was absolutely gutted inside). I held it together until she left. But I know I left a good impression on her.
I certainly wasn't going to make it easy on her by acting crazy, or desperate or angry. That's what she wanted so she could leave absolutely certain she had made the right call.
Just keep cool and calm. If you are going to break down, do not let her see it. Hold it together no matter how bad you feel.