To me it doesn't sound so much as you are jealous but that Dis has always been "your thing" and you were hurt that she didn't come to you for advice to make her vacation great but has ended up having a fabulous time anyway... I know my sister has been eager to help us schedule, plan and make the most of every second of our up coming vacation but we're very different people- she wants to take in every single thing or she will feel cheated out of part of her vacation as she's got it in her head what are things she must do, where as we're more stop and smell the roses type of people- anything we see and do will be a huge bonus for us so we're not going to feel cheated out of missing things we miss as we prefer a less scheduled approach with 4 small kids.
I would look forwards to the fact you'll now have another thing in common as friends- a love of disney vacations!
You're right--it has always been our family's thing, and they have never showed any interest in it at all. The only reason they were going, in the first place, was so their daughter could play in the tourney. I think that it will be nice to share this in common with them now!
Thanks for the advice!