Jacen
What matters is what you do now. There are not many upsides to being kidnapped by a mystical seal and whisked off to another dimension from which you can't escape, but that's one of them. Now you can be the big brother you want to be to her.
It'll take time but I think you guys will get there. If she has to invite friends over you can't stand, then at least it's a step in the right direction. Think of it as her sharing something with you?
People are going to be on to you if you count to sixty.