I think bitcoin could well reach $2,000 - $3,000 if this $6,000 support get's broken. If you would sell now chances are high you could buy back and thus double your btc holding.
This is not financial advice, just a thought.
And this is not a good year for crypto I believe. Late 2019 we'll see some action.
Selling can be anytime, but I think if you sell and want to buy back at 2k price it is very unlikely. I think bitcoin will not fall in the 2k price.