furiously; with anger; indignantly
Fixed adverbial phrase meaning 'with anger poured into one's words or actions'. Used when someone speaks or acts while clearly expressing anger.
See also: 込める
彼は怒りを込めて抗議の声を上げた。
He raised his voice in protest, filled with anger.
怒りを込めて手紙を書いた。
I wrote the letter with indignation.
From 怒り (anger) + を (object marker) + 込めて (te-form of 込める, 'to put into'). Literally 'putting anger into (one's words/actions)'.