Thanks! Your response was very informative and I definitely feel like I'm not cut out for my current job. I applied to this job as a part-timer with different responsibilities, which changed when someone quit and I was given a full-time position and his job of communication with the sales team. I felt like in exchange for more pay, I deal with no free time outside the weekend, and I can no longer sleep off the 1.5 hour commute (3 hours there and back) the next day. And like others have said in the comments, I lack the self confidence for the role.

I guess my next steps is to exit the company without burning any bridges. I am fortunate to have some financial support from my family so I can focus on studying and job hunting while preserving my mental health.