I'm going to tell my girlfriend how I feel
Have you not been honest? Why do you need to do this?
I seem to be tired of pretending.
No matter how you feel it's good to be honest. Pretending longer will just eat you up inside.
Yeah, I have never liked her.
I am glad you are going to tell her the truth. She will probably have hurt feelings but it is better to end the relationship now before it drags on longer.