i agree with the above
we had the same issues with sarah it took a while and the green eyed monster still comes out from time to time, but we made sure that she & dh had there time togeather to do things without jett around and also the 3 of them too,
we explained to her that she had to let jett have some "fun time" with dh too and how as he was a baby he cant run around and play etc and he didnt understand why she was getting so angry and frustreted at him and that when he was older he would want to play with her all the time
and now 2yrs later its definatly doubble troubble at our place although she does still get jealous of things
good luck