In need of advice

I joined a co-ed fraternity last semester, but now as time goes I realize that I don't wan to be apart of the organization anymore. I recently had a falling out with one of my close friends ( we both pledged together and went to same high school), and the fraternity does nothing for me. I want to quit today, but I also JUST received my mentee, and I feel like I would be letting the girl down, as well other ppl in the fraternity if I just up and quit. I'm thinking about just waiting until the end of the semester but id really like to move on with my life and join other things that I actually want to be apart of! What should I do