App to send mass twitter direct message

I need a simple app that can take a list of my followers and send them a dm on twitter. It should support a mail merge type function. Example: "hi %handle% this is my message" in this case the variable should be filled with the handle. Best scenario is to work with a google sheet. Each column name is a variable. Keep it simple. Assume the first column in the google sheet is the twitter handle. The app should take input of a timeout and max to send in batch. Progress of send and any error message from twitter should be reported back to the user. Chrome extension may be the way to go but I'm open to ideas. I have 8000 followers so large numbers need to be supported with timeouts, etc.