How can you pause text to speech so that it restarts from where you left off?
This is a feature people wanted for a long time but it never came. An alternative is to use voice over but it doesn't really allow you to read out loud the highlighted text, it has to be the entire document. To activate it the default shortcut is command F5. You have to enable it in setting, just search for voice over.

There is one other way. You can save the entire document as txt file and open it with any browser of yours, tested on chrome or safari. Select all and right click, then "add to itunes as spoken track." It will take a few minutes and then you will have an audio file you can play. Press pause key on the keyboard to pause or resume while reading.