My manager got pissed with me?

I never miss a shift, but tonight I was apparently scheduled on for one, my manager contacted me asking if I was coming to which I responded my shift had a cross through it. He proceeded to get angry with me saying it didn't and that I was scheduled on. My work is already pretty shady in that they do things that are more or less 'illegal' regarding roster and pay. However they have been generally good to me and still pay what they promised. Regardless, I re-checked the roster to make sure I hadn't messed up, and I was right, yes there was a time written but it had a line through it. Any other time this has happened it meant that the shift had been cancelled. I proceeded to send him the roster with the crossed out time circled, and to add to this there was no way I was making it in as I organised to work on a project hours away for uni thinking I didn't have a shift. He told me that it wasn't cancelled but it was what it was at this point. I already have major anxiety, and I hate being seen in a bad light, but I'm also annoyed because I don't believe this was my fault. Honestly I've been wanting to leave this job for a while but I've stayed out of loyalty, I just don't know what to do as my anxiety makes me overthink things and this is stressing me out.