depending on who this person is, and how significant the thing they did was to make you want to drop them.
If it's a friend or random person, break off contact. literally, just start ignoring them, they'll get the message and (depending on the person) they wouldn't want to put the effort in themselves by reaching out continuously.
If it's someone...... reply
If it’s in real life then stop showing interest in them and if it’s online then start ghosting their texts until they eventually don’t message you anymore reply
