Are you fetching this out of a database?
1: I would first get the length by applying $copy = strip_tags($yourContent); Now you can measure accurately 3000 characters, but what if a word gets split?
2: Then you could do a regular expression to match maybe the last sentence from the copy. strstr(substr($copy, 0, -50), …
Err actually, this is a tricky one, but I tried to get the ball rolling