worse than the bad grade may be the feeling of having disappointed those people, like parents a

worse than the bad grade may be the feeling of having disappointed those people, like parents and

may的倒装句，
正常语序“ the feeling of having disappointed those people, like parents and parents may be worse than the bad grade.”
those people 是having disappointed的宾语
译文为，比差的成绩更糟的是让其他人，例如家长和老师，失望的感觉。

Those people 是宾语，parents and teachers 是修饰those people 的。
整句话的理解是：糟糕的成绩会让老师和家长那些人失望。

worse 主语，than the bad grade 主语的定语从句，may 情态动词，be 系动词，the feeling 表语，of having disappointed those people，like parents and teachers，of形式的定语，修饰 the feeling。主语+定语从句+情态动词+系动词+表语+定语。those people 是定语从句中的宾语。
整句意思：比差成绩更糟的事儿也许是令像父母和老师这些人失望的感觉。