There is a fine line between giving feedback and putting a person down. It tends to be how the comment is received. Without knowing the situation and what was said it is impossible to know what the situation is with you. I think you need to ask yourself, are they putting you down or are they telling you what they really think? These are different things. What makes it seem like a putdown is that you do not want to hear it. If they are truly your friend I expect they want what is best for you, sometimes being a good friend means telling your friend they are being an A-s-s. Only you know what the truth is.
Some people have a hard time sharing friends. Sounds as if she is feeling threatened that you will stop being her friend. All you can do is reassure her of that and tell her that putting you down isn't making the friendship stronger. Maybe she will wise up.
Friends don't make fun of each other Friends support each other. End this friendship.
:( hmm try to talk openly .