Embracing Islam secretly

Q: I have a friend and she is really inspired by me and my religion. I am a Muslim. I told her about the importance of Islam and why she should embrace. She looked convinced but all of a sudden she said that she will get family pressure if she embraces Islam openly. I told her to convert her heart as Allah sees whats in the heart. She has accepted Allah as God and Muhammad (sallallahu alaihi wasallam) as the last prophet. Is this allowed? Will she still see hell?.I hope she sees jannah. I dont want her to go in hell. I want every friend of mine to join me in jannah. 

Taking a false oath when dealing with a psychological patient

Q: Our elder brother is a physiological patient and on drug abuse. We tried to convince him for treatment but he refused. We started an outdoor treatment with a physiologist. In this treatment we teamed up with the psychologist and started his physiological treatment in which we perform different types of therapies. We changed our behaviour towards him and made different approaches. He is almost 75% recovered now.

Recently he started doubting us that we are doing some kind of treatment without him knowing. He started fighting with us and we denied doing any treatment as the doctor told us not to tell him at this stage. He is now asking us to put our hand on the Quran and take an oath that we are not doing any treatment for him. The doctor is advising us that after a few months, when he is fully recovered, then only should we will tell him the truth.

What does Islam say? Should we take a false oath to satisfy him for sake of his recovery and later, when he is fine then tell him the truth?

Suspending a talaaq

Q: I said to my wife. "Agar bazar se ik ganty ke andar wapus na ai to sub kuch khatam hojai ga" with the intention in my head to scare her that the rishta will end so come fast and not at all with the niyat of talaq. Now after 3 months I did researched and found out that this is called kinaya and it may be a divorce?