Having a struggle with linebreaks/carriage returns


I am having a bit of a struggle with line breaks when I import lessons. If I import text with single line breaks (it makes no difference if they are Windows, Mac, or Linux breaks) something in the text field strips the single linebreaks out so it comes out as one block of text. If I replace them with double linebreaks they get replaced with p tags, which is fine (although I would prefer single br tags, or at least less space between paragraphs). However if I then edit the lesson the editor adds double br tags to the existing p tags and I end up with the equivalent of quadruple linebreaks. (See attached image)

I thought one solution was to go though the lesson by hand and replace all returns with shift+return, but, as you can imagine doing this on a long article wastes a lot of time. Also, even if I do this, if I then copy some of the processed text and paste it into a different lesson the editor strips out all the shift+returns that I put in.

At the minute I have the choice of no returns or four.

Can you give me some advice how to reliably just have single returns in my lessons?