Match everything delimited by another regex?

Question

I'm currently trying to make a regex that will find all the sentences in a block of text, and so far I've got this;

(?=(?<!mr)\.|(?<!mrs)\.|\?|!)+

Which will find everything that delimits a sentence. I want the regex to find everything that's contained between what this regex finds, but I don't really know where to go from here.

Answer 1

(Moved from your closed newer question)
In your case, the lookbehinds should come before the periods.
Condensing your expression, it is

Update - Between it you could just split discarding delimiters

 # (?:(?<!mr)(?<!mrs)\.|\?|!)+

 (?:
      (?<! mr )
      (?<! mrs )
      \.
   |  \?
   |  !
 )+

Or, split keeping delimiters

 # ((?:(?<!mr)(?<!mrs)\.|\?|!)+)

 (
      (?:
           (?<! mr )
           (?<! mrs )
           \.
        |  \?
        |  !
      )+
 )