What should I do

I liked this guy for almost 4 years until when things went downhill like he gets mad at me for simple things and started to get a lil toxic so we stopped talking and I thought I didn't like him until I saw him with a girl in the hallways laughing and doing things we did before we stopped talking, I really wanna confess but we aren't in good terms so I tried texting him but he left me on opened, what should I do?