meth questions, this is serious and i need help PLEASE?

alright so my bestest friend ever
did meth three months ago,
for 2 weeks, everyday.
my friend claims she did it because it was “fun”
i did not know about this, she never even told me about it. and me and her were closer than anyone. it was real love. (we werent dating or anything)
so anyways, she found out that i dropped one of my other close best friends because she was doing drugs,(and she is best friends with this person too)
and then the day she found out that, she quit doing meth.
a month after she stopped, my other best friend told me about it, and says she is sorry for not telling me about it before. i dropped her as a friend too. because i felt so powerless, i even asked her before because i had suspicion of it, and she denied it. i felt powerless because i could have done something about it.

i approached her, i ask “have you ever done meth before” saying it in a weak voice.
she paused and told me “yeah once”
then I said to her “then why have i been told that you have done it everyday for 2 weeks.”
she told me “be cause it was something to do, and everyone was telling me come on just do it, so i did, and it was fun.”
this is the part that scared all faith outta me, she continued her thought “it made 2 weeks feel like 2 days!!” and then she LAUGHED. she laughed!!
i asked her why she stopped
she claimed as soon as she found out i dropped some other best friend for doing drugs, she immediately came to the conclusion to stop. and then she said “i stopped because i didnt want to lose you”
i was very disapponted in her, i retorted, “well if you do it again you WILL lose me”
she knows im serious.
but sometimes i feel that she knows i give her lots of chances and takes advantage of that.
I’m 100% sure she hasn’t done it again since, I have MANY MANY friends, and many of those friends are constantly with her, and are druggies themselves. they would have told me and or i would have heard by someone. and i havent had any suspicion of her doing it.
i also forgot include some other details, the day after i approached her about it i said to her “you know what meth does to you.. right?”
and she said yes.
i showed her pictures anyways of mouths that look like the inside of vaginas but with a few teeth.
she said “yeah i know what it does”
and i said “so why did you still do it”
she said “idk i didnt really care”
some other details,
I asked her the next day after that, if anything happened between us would you start doing it again.
she replied “idk maybe.. probably”
i was very shocked. started crying. the next day, she started talking to me on the phone, and then brought up she wouldnt do it again if something happened between us.
i have alot of trust in her, after all, it feels though we were ment to be friends forever. we grew up together basically. been friends for about 7 years (we are both 15 years of age now)
and she feels even more passionate about me.
today, its been three months since she has done it.
she told me that some guy that she was going to snitch on her
so that guy told her parents she has done meth
they said they were going to send her to rehab. this took place last night.
but this morning they changed their minds.
she hadnt told me about this until 4:00 this afternoon, while we’ve been hanging out for about 2 hours.
so my gut is telling me she didnt want to tell me about that but she felt as she had too.
i asked her right after she told me, “will you promise me you will never do it again”
she told me she cant promise because she claims nobody ever knows what will happen in the future, as if she were to get drunk and then meth would be offered to her.
but she still claims she doesnt want to hurt me so she wont do it,

I reminded her, “if you ever do it again you WILL lose me”
after three months of not being over it, she knows im serious. i can tell.

she tells me pretty much everything, once we dated and she told me she cheated on me before. she was drunk of course, and told me the day after the party.
my questions are,
is she addicted?
do you think she will do it again?
should i have to worry?
if she is addicted, at what time will she truly be free of addiction. months?? years?
thank you for listening i very much appreciate your time.
after some other events, she quit drinking and smoking pot. like literally no joke. no questions. when she said she quit drinking i chuckled a bit because i think thats just ironic.but she was serious and committed to it, i drink occasionally and she wont even drink with me. even the people she hangs out with tell me she doesnt drink when i ask them.