"FEELS" HAS BEEN A LEGIT TERM SINCE AT LEAST 1782:
— The Duchess, by Amanda Foreman.
Georgiana, Duchess of Devonshire, really wrote a real letter to her mother complaining about the feels in 1782.
I love everything.
There’s also the 1917 letter to Winston Churchill, with the first recorded instance of OMG, which can be read in full here.