"Hello, I just got married, so I'm letting everyone I use to date or flirt with know my new status. I'm reaching out to you to let you know that I can no longer be in contact with you. I know it's been awhile since we have communicated, so this should not be a problem."

Also, he CC'd his wife, and it was obvious that he BCC'd whoever else.

She broke up with him maybe 7-8 years ago, and he would occasionally text her with small talk 1-2 times a year. They probably haven't seen each other in over five years.