Three words... F this job

Let me start with this. I haven't even been here 90 days yet. I've worked 3 jobs before this. All of them being temporary part time jobs. This is BY FAR the worst one I have had yet. I enjoyed the first month or so, but little by little it became a living hell. Managers are difficult to talk to, often avoiding having the needed conversation. I am a eucharistic minister at my church and that requires me to be off by a certain time each Saturday. I have already sat down and talked with my front end manager about it, and he agreed to it. But when it came time, I was working later then we had discussed. That brings me to my first question. Is this normal??

Next. I have had mental health struggles for the majority of my life. My managers know about that. This past Monday I had a mental health breakdown and it resulted in me missing work. (Yes I know I'm a bad employee for that) My father called to let the managers know. They were completely understanding. That's not where the problem is. One of the baggers, (let's just call him John) was going around telling all the employees and customers that I missed my shift because I had a mental crisis. I am in the process of filing a grievance because of this. Anyone have advice??

Lastly, one of the office helpers/assistant managers got in my face the other week and barked at me to do something that I was told NOT to do. How should I go about this?

Quitting the job is out of the picture because my parents (who still pay my bills because I'm 19 and live with them) have said that all my stuff is being taken if I do. If I stay it is only a matter of time before my mental health RAPPIDLY declines.

ANY HELP IS APPRECIATED!!!