If she's an old friend, just tell her (as an old friend) that you're not interested in her tweets and that's why you're unfollowing her. To rely on third-party

If she's an old friend, just tell her (as an old friend) that you're not interested in her tweets and that's why you're unfollowing her. To rely on third-party services to avoid dealing with interpersonal relations is what is known as "being passive-aggressive". Anyway, it's not like you're calling her baby ugly, it's just Twitter.