Buffer Limit on Whispers?

So is the limit to how much text you can cram into a whisper? I ask because several times I've copied and pasted fairly large blocks of text into a whisper only to see the first part of it remain secret between me and a player but the rest spills out into public chat. Is this because of a character limit or is due to something else like a weird escape character getting into the input? What is the character limit, can someone give me a hard number?.

The issue is the line breaks. You need a new whisper at the start of each line.  You might be be able to wrap it all in {{ }} but I haven’t tried that outside the API. 

Thanks, I'll keep that in mind.