My feelings of jealousy and frustration about my best friend are really getting me down.
Oh, really, why is that? What are you jealous of?
Everything is going so well for her, and it isn't going well for me.
It's perfectly normal to feel a little jealous from time to time, so long you are genuinely happy on your friend's behalf. Maybe you should talk with them about how you're feeling so you can get a better perspective on your emotions.
I don't think I want to talk to her about it.
It's fine if you don't want to talk, but I just don't want to see jealousy get between you two. Feelings of jealousy are normal, but if it gets out of control then it might really hurt your relationship.