I realise that something saved my life

I was 17 and was on the verge of committing suicide. It was on the very day that I decide to end my life for once and for all. I went up to level 12 of my HDB flat, ready and prepared. However when I look down from level 12, something make me stop and soon later I decide not to do it. For a while, I regret that decision. As time fly by, I realise that something saved my life. Till to today, I still wondering what was that something that make me stop doing it. At the same time, Im afraid that I have the thought of committing suicide once again.