You got quite a situation here with your personal life at the
moment, but do not fret over it as it happens to
everyone...including me. 
I understand your dilemma over here...you do not want to lose your
best friend to other friends whom you're not close to. Fear of
losing a friend whom you can trust and hang around with is indeed
terrible as nobody likes to be alone in this world and it's almost
like the feeling of betrayal, jealousy and disappointment.
Friends come and go in our lives, so why does our friendship with
our good friends turn sour? The reason is because both us and our
friends lived differently, have different priorities in life, have
different difficulties/burdens/commitments in life, and of
course...different personalities. When two people became friends
and come together and walk down the friendship lane, there is
always a reason that brings both of them together. Sometimes you'll
wonder why he/she is friend with you after being friends for a
while...and you search for a reason before you actually admit that
person to be your real friend. So...what was the reason that
brought the two of you together? If you're confused about this,
then "Houston, we got a problem".
The reason behind good/best friends is that they both can't live
without each other's friendship and knowing that they are at least
still real friends even though they don't contact or hang around
each other every single moment/opportunity. Oh...and don't use the
term best friend unless you want to go after that best friend. Best
means only one, so when it is said to the opposite sex, the meaning
is changed to "I like you and I want you to know that I'm your 1st
runner-up in your queue. So if there's a vacancy in your
relationship throne, please let me know."
Okie..if you have already thought through thoroughly that you die
die must own this good friend of yours, here's what you can do.
I called it "Infiltrate, Take control and Eliminate" Hehehehe....
Infiltrate will not be easy cos her friends will be shooting at you
on sight and poisoning her mind like Poison Ivy would. So please
make sure you got your extra skin on as it gotta be thick enough to
bulldoze into that fellowship of the ring. Since your situation is
such, I would suggest an apology is necessary to restore her
friendship with you. Do not tell her the truth behind your actions
that you're feeling insecure, jealous and you can't live without
her. Cos that's going to make you uncool. Hehehe...I forgot to tell you, you're supposed to be her
cool friend once again. And she should at least be thinking of you
as such...gracious and cool.
Your friend will of course graciously forgive you and kiss and make
up. (If not, maybe you're not a friend to her afterall and should
go bang your head against the wall for feeling so bad over it)
Although things will be slightly different as you can feel it so,
but do not worry about it cos things are going to get better from
here on.
Next, you need to blend into her group of friends. Not that
difficult if you do take a genuine interest in her friends. The
keyword is "Listen" and paying attention. Everyone got their own
stories to tell, gossips, sharing news and tips. Do not ask
wide-end questions like "What DVDs do you own?" (provided the
target is a dvd/movie fan). Because this question is going to force
the target to generate so much answers and it's going to give her a
headache that's going to put her off after that. Instead, ask
specific open-end questions like "What's your favorite DVDs?".
Once you've blend into her groups of friends, it is time to Take
control.
Take control is easy. It involves in organising activities for your
good friend and her invalid friends. If you have been "Listening" and taking some genuine
interest in her friends, you should be able to know what kind of
activities would interest them and bind them. Note that participation level need not be 100% as you
simply cannot babysit everyone. But please make sure that
participation is at least 70-80% provided she has 10 friends.
Keep everyone happy, satisfied, enjoying with some laughter and
smiles. (Treat them Happy meals if you really have to) And please organise fun activities several times until
you're sure that you're undoubtedly their unproclaimed cult leader
and recognised friend.
If you have achieved that level...well, you're already a queen
among them isn't it? Although it's time for Eliminate and Elimination of your
former enemies, I won't tell you how you're going to do that.
So..do that at your own discretion ok?
If you can do half of what I'll advised...you won't lose your good
friend. But even if you decided not to do any of those, you can
still salvage your friendship. Afterall, she's just a phone call
away isn't it?
You see, friendship and relationship are similar in some sense.
Both have to be voluntarily...and that's is a very important key.
Both have to be interested to becoming each other's friend to begin
walking down the friendship lane. So do not be demanding to your
friends, do not even expect them to hold on to their promises or an
agreement. Disappointments hurts and it hurts even worse in the
friendship department. So...to have a healthier friendship with
your friends, eliminate this disappointment disease from your
system for good. Just remove expectations, holding onto promises
and such...cos we aren't living in a fairytale.
Just one more thing before I end this...You need to feel good about
yourself at all times or nobody will feel comfortable being your
friend...
Anyway good luck, I wish you all the best and have a pleasant year
ahead.
