Interesting turn of the thread, there.
I do have personal experience with rape, having been on the receiving end. I've also spent a lot of time with abuse victims. Personally, I didn't find Sheyza's attitude or words offensive, but then, I'm a pretty easy-going person.

Sheyza, some reasons your mother might have kept quiet for so long is this: Being raped is plenty traumatic all on its own.  Since the rapist was her father, if she told her story, the result might have been (probably would have been) just more trauma.  Family freaks out.  The risk of not being believed.  The risk that she might be believed but then nothing would be done (and I've seen this happen--some mothers suck.) That the best possible outcome was that she would be believed, and something would be done, and then everyone would know, and think of that every time they thought of her--which shouldn't be a big deal, but to a teenage girl, can definitely be a huge deal.  If the rape was a one-time thing, and not ongoing and repeated, it might have just been easier for her--at least at first--to just keep quiet, and try to keep life "normal."  Some people in a sort of emotional shock get hysterical, but others just retreat into themselves, at least for a while, to try and sort out what's happened to them--that's what I do.  There is also sometimes a weird sense with this sort of thing that once you SAY it, you make it just that much more real; someone else knows, and you can't take it back and pretend it never happened.  So long as you keep quiet,  you can pretend to yourself that you have the OPTION of acting as if it never happened.  I don't know if any of this applied to her, but any of it could have.  

Also, btw, I understand what you meant about how she "never looked back."  That's sort of how I feel about it.  It happened, but I don't feel like the walking wounded because of it or anything.  There are bad people in the world, and one of them got way too close to me.  Life goes on.