I don't want to keep messaging this girl
Why do you continue to message her then?
I want to know if she is still interested in me, regardless of how I feel.
It's fine to not want to message her. If she has feelings for you, she will let you know, but she might get upset if she keeps getting messages from you and lose interest or become annoyed.
I will stop messaging her right now.
I'm glad you decided to stop. I hope things work out with her and she lets you know how she feels soon.