You don't like my sister, so much so you nerver asked her to go steady,

or

You don't like my sister, especially because you nerver asked her to go steady. bu doğru görünüyor mu?

Of the two options, I like the first sentence the best. However, I'd say it like this:

"You don't like my sister, so much so that you never asked her to go steady."

Or

"You don't like my sister, so you never asked her to go steady."

Your use of "especially" in the second sentence makes it sound to me like the reason this person doesn't like your sister is because he didn't ask her to go steady (which is an odd reason to dislike someone).

In a sentence like that, to use especially, I would say something like: "You don't like my sister, especially because she turned you down when you asked her to go steady."