spiteful
adj.behaving in a way that is mean or cruel just to hurt someone else. You use this to describe someone who does something annoying on purpose.
adj.behaving in a manner intended to cause harm or annoyance to another person. Often used to describe actions or words that are deliberately cruel or petty.
“He made a spiteful comment about my new car.”
“The spiteful remarks from the former colleague made it difficult for the new manager to focus on her work.”
“The spiteful nature of the letter suggested that the author was not merely seeking to settle a dispute, but to ensure that the recipient would feel as much pain as possible.”
From Middle English spytefulle. By surface analysis, spite + -ful.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.