as the note wud be confusin they wud not understand what u wud be sayin but after u establish no contact they wud get an idea… don’t block them, just no contact. if sensible, they wud keep that letter with them and the memories of u, if not… find someone who wud keep that note.
do a breakup by writin ur lover a note on a linen paper sayin that u don’t love them anymore in a very sophisticated language, they wud at least appreciate the effort and u wud be the sweet ex they wud talk abt later