Did I do the right thing?

As I said in my vote, you should have kept them there at home while maintaining a naturist household rule/practice. Since you were new to nudism it was pretty normal for you to start having sexual thoughts about the nudity even if they were your daughters. It's something you should have worked out in your mind as you all got used to the family nudity. Over time you'd have gotten so used to it you'd no longer notice anybody's nudity because you'd have accepted it for how natural it is.

If you feel that sending them to your sister's was the wrong thing, I think that you wanted to protect them from yourself and thought they would have be better off with your her. You may have been wrong, you may have been right. Either way, you wouldn't have been able to foresee it then. And you shouldn't feel guilty that your sister messed them up.

If you feel that starting letting them to go nude in the house was the wrong thing, that depends on your motives and methods. If you wanted them to be unrestricted, nothing wrong with that. If you wanted to see them naked, that is not necessarily bad either but it depends on who you ask. If you FORCED them to be naked, yes I think that was a bad decesion.

But when all is said and done, your daughter's decisions are her own responsibility. It's entirely possible that she would have ended up 'messed up' anyway and she may or may not have blamed you, even if it really wasn't your fault. I've heard of children suing their parents for having them circumsized. They feel they are messed up just because they couldn't experience sex in every way they could have. And that's a very socially acceptable practice.

So if you didn't force them to be nude and you wanted them away from you for their own protection, then I can't see how you've done anything wrong.