Hi op
I wasn't addicted to cocaine- mine is prescription painkillers eg dihydrocodeine. I've heard a bit about cocaine through NA and of course know about addiction in a general sense.
The withdrawal from cocaine isn't physical - the only physical affects really are being tired, chills and sweating, feeling restless etc. Certainly not the horror that's opiate withdrawal. Its very intense emotionally though - at least on par with opiates, but on heroin for eg you've got the crippling pain to distract you whereas on coke you're stuck in your head. Anxiety, depression, restlessness, lethargy, no motivation, angry, fed up etc - all the usual things really. The one thing to be careful with cocaine withdrawal is that confusion and intense thoughts can lead to suicide attempts.
You say she's getting support, what does that involve? Would definitely recommend getting in touch with drug services and trying NA.
In terms of what you can do - support her and be kind. Recovery is fucking hard. You get so angry - all your emotions are coming back and you know exactly how to stop all the discomfort (mental) but you can't use and it is so frustrating, unfair and there's a real sense of hopelessness, feeling there's no way out and not wanting to die but just wanting it to stop. Anger is huge - you feel so angry about it all. It's a proper uphill battle that no one in RL understands and no god talk or na platitudes help. Sadness is a big one too. You miss it, it's like a close friend has died and you feel helpless
Realistically, very few addicts stop and never relapse. Chances are your friend will. In that situation, it is so important you don't judge her or criticise or try the tough love bollocks. It just hurts more. Protect yourself obviously- don't give money, etc etc. But keep a dialogue open even if that's only by text. Ring every few days and check how she is. Offer to give lifts to meetings etc. Don't make all your discussions around using - trust me when In early recovery it's in your head enough and painful enough, so you do not need others bringing it up constantly. Reassure her that relapse happens and it's normal, and support her. You must understand that relapse is normal. It isn't a failure or a sign of weakness, it's reality. It happens and they're beating theirself up, they don't need more.
Be a friend, be kind. Withdrawing your friendship isn't a good idea (unless it's necessary for your own health and wellbeing, and protect yourself) and does no good. Tough love is an outdated concept made by people with no idea about addiction.
Understand that relapse happens, as above it's normal and in a way to be expected. The drug has been your crutch for so long and all of a sudden it's gone. You need to deal with real life and emotions. Anger, sadness, boredom, depression etc etc. You're also dealing with the consequences of using eg debt, so some practical advice and support wouldn't go amiss. She is likely going through the toughest time of her life right now and needs some support to get her through. You can't imagine what it's like, I couldn't understand the bloody difficulty and sheer impossibility of it all until I faced it . All you can do is help her through it.
Thank you for taking time to wonder how you can help. Most people don't even bother trying to understand, you're clearly s good friend