Dude, let it go. Making a big deal out of it will probably just come off as a "Let's Make It All About Me" moment, even if that's the complete opposite of what you intend. You said you "foolishly" had been "clinging" to this idealized version of your relationship---I think you kinda already know that you, as her sibling, need to let her go. After all, she's a well-rounded, functioning adult who has gone out into the world to live her life. That's what you WANT her to do. Be happy for and try not to dwell on the fact that you might not be as close as you want right now.
Besides, relationships change, people change, circumstances change. Such is life, my friend.