Friend addicted to weed

A friend of 20+ years has become addicted to weed over tbe past 3/4 years.

We're both in our mid 30s, she was in a relationship with a guy for a few years, it was chaotic and he wanted then to be open until she dumped him and agreed to be monogamous and from then on she sort of did whatever he wanted. He wasnt a horrible guy, shes just attracted to men that are a bit rough round the edges. She smoked weed casually prior to that but it worsened whilst they were together as he grew and sold it.

He split with her 18months ago, because she was so addicted to it and was no longer herself.

Shes always been a crap pal, theres 6 of us in our group and two of them make little effort, only showing up to things, not initiating etc. The past two years weve all become sick of her. She seriously embarassed one of our friends by coming on to pretty much everybody at her wedding (including couples) and i mean asking them back to her room levels after a couple of minutes of conversation.

We tried having a bit of a gentle intervention to say how worried we were that she leaves things early or is always off work sick and she said she would talk to her GP to increase her antidepressants

That was about a year ago now. Since then shes not improved any, has been given numerous warnings at work for her volume of sickness and time off (shes a school teacher in a high school) and for behaviour at work events

She swings between dating and not and is just so against any sensible men, we swiped for her recently on bumble, she met the guy, and deemed him boring for not kissing her 40 minutes in...

Shes also now begun having repeated periods of serious vomiting and nausea. The first she told us about, because she had to cancel seeing us, the most recent she barely mentioned and even then, she lied about the longevity of it. Saw her on friday and she looked horrific.

I believe that shes started experiencing hyperemisis induced by her weed use.

She told a friends mum shes addicted at a hen do we had, but laughs it off if we bring it up, she says she smokes about £150 worth a month (presuming thats her downplaying it)

And her dad keeps on helping her with her debt.

She refuses to meet up or do anything without having a joint at home and then leaving after four hours to go home and smoke loads. Even if we have a chill night at each others homes she will chose to taxi from her work to smoke then to the other girls spending 100 quid each time to do so because of how far she lives.

I would like to write her a letter or speak to her mum as she is soo soo extremely avoidant but the other girls dont want to have to get involved (3 of them have experience of addict exes or parents and find it triggering)

I want to help but shes also not given a fuck about my mum and MIL having cancer recently, has started being aggressively rude and i dont want to waste energy for someone who doesnt care for us.