Upset at work

I work hard and do the best I can with my depression and OA. I got so upset last night as the pain in my body was so great, the meds were not helping and I was trying to handle it. I had to work my last hr alone and a lot of customers came into the store. I was really on the verge of a break down. To top that all off the co-worker who was supposed to relieve me at 10 phones at 10 saying he's going to be at least 20mins late!!! I got so upset and angry, I was in so much pain and couldn't go to sit sown because I was the only one there and when he did finally show up I didn't say anything just left for home. I have to learn to speak up. This wasn't the first time this has happened! He does know about the OA but he is more tuned into himself. We're both assistant managers and he didn't even apologize for the lateness and grinned instead. That Hurts!!