Here's my own rewrite. At points I've changed the phrasing to something I feel is more natural, but I'm not a professional proof-reader so perhaps other people will query my changes.
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The night before I had to attend the interview, I worked on the essay I had to submit. I asked my uncle to help make sure that the wording[?] was correct, and he also taught me how to behave during the interview. I felt very confident and sure that I wasn't going to do badly. When it started, I acted professionally and I talked about my life, my career path, and all sorts of other matters. The interview did not last long, and I left feeling confident that they might consider accepting me into the [program/programme].
I waited a long time in school hoping for a response. Eventually, I asked my college consular about the issue and he told me, “I'm afraid it's not happening.” Twenty people were accepted into the [program/programme], whereas I was one of only two people to have been rejected. That made me feel embarrassed.
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