13.5BTC is really a huge amount nowadays to but you made a good decision maybe it has been a long time that I have not heard or seen that such a huge amount of money is being traded from users here in forum or any other guy that I know which unfortunately deal only on deal under 1 bitcoin.
If you want my suggestion then I would suggest to split the budget and try the altcoin too, it maybe sounds unfamiliar to you but the altcoins is a huge market and with a high potential to earn a good profit but also to loose as there are many many project that are pretty good that have added many features that bitcoin does not have.
Different thoughts around the world about the future of bitcoin. In my point of view we should speculate better for the future of bitcoin and dont be panic. Falling of the price is normal because it is crypto and we cannot anything about the coming situation of the market. What people want and think about bitcoin and what are their expectations from it fall in ambiguity, but patience and courage will take us in better situations.