I'm not sure about lexapro in particular, but I have supported others through the same thing before and the first week is usually by far the worst for the physical symptoms of withdrawal. After that it's more a matter of her now being medication free and having to face issues that may have been covered up while on them. This can be quite confronting and overwhelming when it happens but it's something you won't be able to help her with much unless she reaches out for your help.
Hopefully nothing worse will happen than already has. It is even possible that the lexapro has been keeping her Depression going as a side effect in itself and she will now be able to break free of the depression. It's something to hope for. She shows great strength in going cold turkey and will most likely have the strength to face what life throws at her without the meds. If she can also ask for help when she does need it she has a better chance again of healing.