Change expectations to acceptance.
Libby doesn't (hate) you Susan, my dear friend.
Libby is as individual as you and I, her attitude towards you is just that (her attitude) allowing her to deal with it other than you carrying the (upset) may help you.
My wife watches me walk up to Mac and say step up, he steps up, (most of the time) when she says "step up" Mac lunges at her attempting to bite, Rose Ann wants Mac to respond to her as he does with me, My wife may (want) this to be...Getting Mac to (want) this also may never happen.
Place Libby on a (isolated) perch such as a play stand, anywhere where Libby (doesn't have the option to get away from the situation), start by standing so far away, just closed enough for Libby to start her behavior.
Continue to stand there until Libby stops the lunging, stay standing there awhile longer, then walk away.
Repeat this with each session getting closer each time, always stay right where you are until the behavior stops.
When you find yourself very close, "within arms reach", reach out and hold your hand there for as long as it takes, when the behavior stops, walk away, repeat each session.
If a person reaches for a bird that is attacking and jerks there hand away each time (the bird wins), this is what the bird wants to happen, and the human is properly trained by the bird.
Hold your hand just far enough away to allow the bird to know and learn, "I am here, I am not going away, I am in control, not you".
When the bird stops the behavior, continue to hold you hand up for a few more minutes, then...walk away.
Biting, all birds will bite, "wanna see my scars", know you will be bitten, don't pull away, curl your hand downward saying a firm NO, let the bird know "you are not going away".
Don't pull away, curl your hand down away from the bite, not away from the bird.
Use the back of your hand, never offer a finger "that comes later",

birds find a finger "small" and "I can latch on to that", but the back of your hand is a larger object, now remember we are trying to change the behavior not a biting issue, "that comes later"

Eventually you will see the lunging stop when you are near the bird, "this takes time".
If any animal senses fear within you, then that fear becomes there tool!
Even the smallest of animals wants you (the human) to FEAR them, after all, this is there own means of defending them selfs.
I know this is a hard (subject) FEAR, but if you show it, they will use it against you.
Yelling VS Firm, yelling at a bird only fuels aggression, a strict NO (firm) without backing down will eventually prevail.
My lovely wife Rose Ann used to show fear, I even sensed her fear when she was trying to get Mac to step up, today, Rose Ann is firm and she lets Mac know, "shes not going away" and by all means there relationship is growing.
The last thing a person should do is offer a finger when trying to get a bird to step up, a well trained bird will step up (well trained).
What about an adopted bird that is used to there previous owner?
The same reasoning applies, but "know" you maybe bit, but if you continue to jerk away, you will always be bit.
Don't pull away, curl your finger in when you sense a bite, out of reach, but don't pull your hand away, a firm NO and offer the curled finger, an extended finger is just the right size for a bite.
A curled finger appears harder to latch onto.
The difference in size of the bird should by all means be considered, after all some of the larger birds can and will take a piece of flesh right off you.
The old saying applies here, start out with a smaller bird before bringing one of the "big birds" into your world.
Expect to be bitten.
Changing any bad behavior takes commitment and please know it may never happen.
I once said to another member, except me for whom I am, not whom you want me to be.
Tanks still bites me every chance he gets, but during supper time, he eats right by my side, buddy buddy during supper time.
Then when supper is over, so is the buddy buddy.....

Thats my Tanks....
I pray you understand my words, nothing I have said was said to offend anyone, hopefully to help you to understand....
The difference from expectations and acceptance.
Arty