10 Answers

Why do you consider her a friend ? If this so called friend is bullying you as an adult you certainly don't have to put up with it , you are not in a school or work place situation, you tell her that when you are in her company she makes you feel uncomfortable or better still walk away and don't even consider her to be a friend.She has serious insecurities,and you are her victim.

She may be jealous of you..or very insecure re herself...why not try talking to her ..and make it clear that  if she were a true friend  she wouldnt be so nasty!..And if that`s the case I`D MAKE IT CLEAR THAT THE FRIENDSHIP ENDS THERE!!!...try not to let her see that her actions are futile and suggest that she may need help!

You need to tell her how you feel. If she still bullies you, move on. She will find someone else to bully.

She is not a friend if she is bullying you, you have to stand up to her, tell her straight that you will not stand for it any longer. Sounds like you would be better off without her .

You'll never please her. The odds of changing her personality are pretty low, too, thus making her a pretty poor candidate for a friendship.

Young lady,you need to tell her straight up that u love her that you have been friends a long time and the Bullying needs to stop.If she can't or won't stop you will have to terminate your relationship.Stand tall and strong when u tell her. this will let her know that u mean business.Good Luck and have a Great Day!!!!!!!

Is she physically bullying you, or is more bossing you around and disregarding your feelings?   Any time you feel bullied by someone, that person is not behaving as a friend. A friendship should be mutually respectful and considerate. 
In any case, this is not the behavior a traditional friend would display.  You feel uncomfortable and abused, and you don't know how to approach her with your feelings. 
 My contribution would be for you to think very seriously what the benefits and disadvantages of the friendship are, what you want to give to and get from a friendship and whether or not this relationship is satisfying and fulfilling.  Are you willing to be subjected to her behavior or have you reached the limits of your incredible patience (20 years is a long time).  Your honest answers will give you a clue what to do.
My other thought is:  If this friend  were your spouse and treated you the same way, would it be considered spousal abuse?  Would you want your children exposed to this relationship? Would you stay?    Could this person be arrested for the behavior?  
My last thought is: Could the abuse escalate to the point where you found yourself in danger?
HOW to talk to your friend?  Straight forward, with eye contact, and a firm voice. No excuses for either of you. " When you (XXXXX), I feel bullied.  It makes me feel (XXXXX).  I need for you to stop (XXXXX).  I need you to (XXXXX).  "

pythonlover

Great advice Bob/PKB

This person is NOT your friend! I don't treat any one that way! 

When she bullies you, put HER on the defense by making fun of some obvious feature about her that's not too flattering......like if she has zits, or too many freckles, or a space between her teeth ( as I do ), or if she's too tall, or real short, or overweight. Do it in front of  other people like she does you.

No question, upper cut to the jaw. Stops 'em right there.