I have not used the app for a couple of years and refused to ever sign up for messenger. I access via Firefox on my LG phone and if I need to get messages I toggle the box that says view in desktop mode. I turn off all notifications. I manage about 15 business pages for clients but I had gone from over 1000 "friends" and over the last two years I finally got under 100. About a month ago I went all the way back to day one when I signed up and deleted over 4000 posts that were not archive worthy. Facebook will still keep those posts for one year to datamine the crap out of them but now I am committed to delete all posts over 90 days unless it is a special event that includes photos of good friends. Most people really do not give a crap about anything over 48 hours.
BTW...this sounds nasty, but when I unfriend them, I also block them. Facebook will continue to show your stuff in their feed and it gets akward. I probably have about 3000+ blocked people because it is the ONLY WAY to try and manage what friends of friends of friends of friends of friends of friends of friends actually see.