Tallgirl, how awful for you but at least you know that the author is not someone whose opinion is not generally respected within the company.
You have been given some great advice so far but I think the hardest part will be staying calm - maybe practice saying what you want to say at home and make sure you take lots of deep breaths so that your voice stays nice and calm (mine tends to go into a high pitched squeak when I am stressed!). make some notes if it will help.
I would go in and tell them what you saw and why it upset you (eg it was personal, insulting aboout you, implying that your employment with the company could be affected by your alleged reaction to being contacted at home during a stressful and hormonal time, accusations are made about you without anyone asking you for your side of the event etc..) and then, if you know what you want from them (eg a personal apology from the author) then ask for it and if you don't know, then ask them what they intend to do about it. I suspect they will want to investigate the matter, so ask them for a time scale for a response and ask them to confirm the meeting in writing by the end of this Thursday - if they don't do this, then on Friday, you write to them and tell them what was said/agreed at tomorrow's meeting.
I would use the DPA as a casual thing along the lines of "At this stage I am very upset and just want the matter resolved quickly and amicably without having to raise formal grievances and looking into the rules on data protection.." and then, if you can manage it, with a steely glint in your eye to show you mean business, say "but if it is not dealt with quickly and to my satisfaction, please be assured, I will take it further because I cannot let something so very unprofessional remain unaddressed"
I hope that helps with some pointers - feel free to ignore it if it is not your style. Whatever you do, good luck for the meeting.