I've found long term success in getting off of Facebook (never used Twitter) using the following steps (I still visit Insta most days on the native app however):

* Got rid of the native apps (except for Messenger Lite) years ago

* Switched to mbasic.facebook.com in the browser

* Recently I logged out of said mobile site

Now every time my muscle memory goes to facebook.com it asks me to login and I close the tab. I don't miss it at all and have no urge to login once I see the login form. I think I may have finally quashed my FB addiction!