Get a vector of handle names of people you follow and have not tweeted in the past 90 days.

get_inactive_friends.R

# install.packages("rtweet")
library(rtweet)
library(dplyr)
library(lubridate)

# Set to your username below
username = 'mribeirodantas'

following = get_friends(user = username)$user_id
get_timeline(user = following, n = 1, check=FALSE) %>%
  filter(created_at < (today() - 90)) %>%
  select(screen_name)