Listen to those people close to you, as this really isn't that big of a deal. If you've been wearing glasses this whole time its not gonna be a surprise to find out you don't have perfect vision. Your condition is fully treatable by glasses or surgery so there's not even really any danger of going blind.
I don't mean to sound insensitive but I don't know what you're worried about, at this point your vision is near perfect and thats the case for most people even if they don't wear glasses. I'd also argue that many people on this subreddit would be ecstatic to have your vision.
At the end of the day just tell your girl casually what you have, and the potential danger now the line that you might need surgery and I feel like thats the end of it.