Very shocked or distraught. I was beside myself when I found out I'd been rejected from my first-choice school. Honestly, we've all been beside ourselves since the funeral.
beside oneself (with something)
Fig. in an extreme state of some emotion. I was beside myself with joy. Sarah could not speak. She was beside herself with anger.
In a state of extreme agitation or excitement, as in She was beside herself when she found she'd lost her ring, or Peter was beside himself with joy-he'd won the poetry award. This phrase appears in the New Testament (Acts 26:24): "Paul, thou art beside thyself; much learning makes thee mad." [Late 1400s]
beside oneself, to be
To be distraught with worry, grief, anger, happiness, or some other strong emotion. The expression appears in the King James Version of the Bible (Acts 26:24): “Paul, thou art beside thyself; much learning makes thee mad.” It uses the adverb beside in an older sense, meaning “outside of,” so literally the phrase means “outside of oneself,” the self in question being one’s mental faculties.