Letters
Send someone a letter, not a text.
You write a letter a page at a time, pick the paper, the envelope and the wax seal, and send it as a link.
When they open it, they peel the seal, take the letter out and unfold it. Each page is written out in front of them, word by word, at the pace you chose. You also decide if they can turn back to a page they've read.
What you write is encrypted on the server. Add a PIN and only someone who has it can open the letter. You can choose how long it's kept, from a week to forever, and a private link lets you unsend it whenever you like.
Once it's sealed, it can't be edited, just like a real one. There are no accounts, no ads and no tracking.