In a new short story one of mine, of the main characters speaks French with English as a second language. As a result his English grammar tends to be 'pigeon' if you get what I mean? In one of his dialogues he uses the phrase, "...for the sea; she is a cruel mistress sometimes!" Now, I'm using a semi-colon here but is that the correct style of punctuation? Would a comma, or a dash work equally well?