I'm jealous of my husbands close relationship with his aunt
Why are you jealous of your husband and his aunt?
Because they always go for holidays together
I know that you like spending holidays with your husband, but being jealous of the holidays he spends with his aunt is immature for a grown adult. If you really want to spend time with him, ask to be a part of the festivities.
I'm going to go and annoy them by being a third wheel.
That is very immature. You should let your husband and his aunt enjoy their time together. If they include you, that is great as well.