I can see why you might feel helpless or have the need for magic solutions, but you probably won't find a potion like that here!
Please tell your friend about your concerns and tell the truth, so that she can make good choices for herself. If nothing seems to work out well, please get someone else involved! Maybe police or someone you can tell about this!
You can try sending good energy to your friend or maybe cast protection spells on your friend if she is okay with that, please stay safe!!