Jealousy is a normal emotion. Its what you do with the jealousy. The grass is not always greener on the other side as others have pointed out, but even if it was, maybe you have a different purpose in life. If you hold on to the jealousy it will eat you up. Allowing yourself to feel all feelings that come up, and talking about them with others and not labeling them as good or bad can lead to accepting them. None of us can have it all. I think we all have to ask ourselves "is doing what we do getting us what we want" and it may be that it's not. On the other hand, it may be that we have made choices consistent with our priorities. I had kids early and postponed education. I got my masters when kids were early teens. It would not have paid me to work after daycare but I wanted to be a stay at home mom anyway while they were young. Sometimes I envied friends that had these great careers and had more income, but I quickly reconsidered when I was at the pool with my kids in the summer and their kids were at daycare.
You are not a bad person for feeling jealous. You are human.