rancorously

/ˈræŋkərəsli/
adverb
  1. In a way that shows deep, long-lasting bitterness or hatred.
    • The two teams rancorously competed against each other, refusing to shake hands after the match.
    • He rancorously criticized every suggestion his coworker made during the meeting.
    • She rancorously refused to speak to her former friend even years after the argument.