Think it would be bad if I told a sort-of friend we took a group photo without her?
Why did you take a group photo without her?
I hate her, but I recognize that there are benefits to being her friend.
It's good that you want to communicate with her, but it wasn't right for you to exclude her. Just because you dislike someone, doesn't mean that you should exclude them from group photos. Particularly if other people in your group do like that person, then deliberately excluding that person makes you look bad.
It's time to let loose and have some fun with this.
Next time you need to make sure she has a chance to get into the group photo. It's mean to exclude anyone like that.