I'm certainly no expert here... But lean on your support system, including us here on PC and don't beat yourself up for anything... Use all your self soothing skills etc. You're intelligent and there is no "shame" in switching jobs, career paths etc or leaving a job you don't like... As I'm sure you'll hear many times, give it time ...

PS have you thought of studying, maybe part time, for something else? (Obviously I don't know what your work is but if you disliked the last job maybe it's the wrong job )

I'm sure you'll receive more useful answers than this

Also personally I wouldn't use the language to myself about "cut out for" etc.. It sounds like my father

I changed jobs quite a bit when I was "in my early" 20's and I didn't feel ashamed. I think it's "normal" (whatever that is)

I know some people who are "still students" at about age 30 - this is a good option for some