Wore out

Every time I have to get ready for work I have an overwhelming feeling of dread that passes over me(along with anger). I am extremely guarded when I walk into work. Just the thought of having to deal with the public makes me feel nervous and angry. I don't enjoy people's company and having a job dealing with the public day in and day out, makes me feel so tired. They want me to pretend to be happy at work and I just can't pretend when I genuinely don't enjoy being there(though I need the money because hey everyone needs a job). When I feel especially backed into a corner(when it's chaotic and I'm beyond frustrated), I feel myself going numb. This has been getting worse and my first appointment is a little over a month away...any advice on how to cope until then? I work by myself in a convinence store, so I can't exactly escape the situation and relax when I need to.