I have no idea what I'm doing and feel defeated

I'm sure depression has a lot to do with how I'm feeling right now. I feel extremely sad and have no clue really why. I'm stressed, tired, overwhelmed, and mentally I feel like I'm not here. I recently went back to school last semester to work on a graphic design degree and today I walked out of my Photoshop class. My mind was absent and I was completely lost. It was only 6 of us in the class and I was behind on the exercise we were working on and I didn't want my teacher to call me out and face embarrassment so I just left. I felt defeated that I wasn't understanding the exercise and was behind. I just feel like dropping out, idk if graphic design is for me...my mind is all over the place. I wanna have a fulfilling career and be successful but I'm so sad and feel like a failure...what should I do with my life