#!/bin/bash

1. Join non-period ending sentences with the next line

sed -e ':a;N;$!ba;s/([^.])\n([^A-Z])/\1\2/g' t.txt > t1.txt

2. Break lines before "because"

sed -e 's/because/\n&/g' t1.txt > t2.txt

Cleanup

rm t.txt mv t2.txt t.txt rm t1.txt

echo "Done!"