I'm having a breakdown

I didn't know where else to come. I usually don't talk about my problems but I need to vent out and blow off some steam. I'm a healthcare worker and my manager always picked on me. I've been with the company for six years. I had some minor issues at work but nothing major. I would show up on time, get my work done and was always available to help my coworker's out when they are struggling. I've gone above and beyond to get my work done and help out my team. I was always complimented and told that I'm a hard worker by my managers who had retired from my job and left. I felt good and matter but now I don't. <br><br>I was written up for being 15 minutes late. I clocked at 715am as I was running late. But had to walk around the building to find the only open door. So that made me about 15 minutes late. I got a written up for that. I got yelled at and called a lazy worker. I work my ass off. I don't feel good. I cried in the car as I felt like I was letting everyone down. I don't know what to do.