I did A LOT of research on the windows before my hike because I am very scared of heights. That was all I was thinking about during the hike, because, if anything, the windows would be the thing that would hold me back from reaching the summit.
Once I got to the windows, I found out that was was worried over nothing. The windows are a good 5 feet wide and not scary at all, it was the switchbacks that I would be worried about. You shouldn't be worried about the windows, instead, you should look forward to them, they offer such spectacular views.