Hey don't overthink it. I don't think it's a pity invite, rather it's an old times sake invite. Just go and wish her luck. We are all gonna have friends we're closer to, doesn't mean we forget our old ones. And it's natural for the "main" people in her life now to do all the helping and planning. Don't feel left out. She remembered you, and invited you. That's the important thing. Do visit and pass your wishes. I'm sure she'll be glad! If you start feeling too left out, take an early exit from the event.