import re
 
para = """I saw this film about 20 years ago and remember it as being particularly nasty. I believe it is based on a true incident: a young man breaks into a nurses\' home and rapes, tortures and kills various women.It is in black and white but saves the colour for one shocking shot.At the end the film seems to be trying to make some political statement but it just comes across as confused and obscene.Avoid."""
print(re.sub(r"(?<=\.)(?!\s)", " ", para))

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