Is investing in halal businesses better than a fixed deposit?

I am working in a Government company. I have started to invest my savings in shares of those companies which are doing halal business for medium term basis (I do not invest in banking, Future & options etc. ). On this my wife starts blaming me that I am playing gambling and started a quarrel with me. One day during arguments I asked her that It is better that you quit my life (Is se behtar hai ke tum mery jindagi se chali jao). I was not having any intention to give talaq to her at that time of speaking these words. After that she said that it is equivalent to talaq bayen (i.e. one talaq). Than I said to her that I do not have any intention to give talaq. After that we both done Nikah (Ejabo-Kabool) without any witness. Now I have three questions: 1. Whether a talaq-bayen occurred between us. 2. If yes, was our Nikah that we performed alone is valid without any witness. 3. Whether Investing in shares of company doing halal business is better than doing a Fixed deposit in Banks. All arguments happened between us only. No other person knows.