My MIL gave me the same advice--but she said to use sandpaper. I LOL'd in her face, and no, and I did not do it!!! As if my nipples weren't sensitive enough from being pregnant, right?!?!
Is this a MIL thing where they are just trying to be cruel? Geez, you would think that having been through it they would have learned...I guess for her it's been over 25 years, so maybe she forgot. It's horrible advice, and mean to boot.
Your nipples will be sore at first, on top of feeling contractions every time you nurse. I remember crying a little. But after a few days, if you stick with it, you actually get used to the feeling and then you don't feel it at all. I also used nipple cream, and I think it helped to heal the skin.
Breastfeeding is really not that bad, and I'm sorry she caused you any worry...but at least she didn't tell you to scour your poor nipples with sandpaper!!!!