I am so going down, when bitcoin went up from $233 to $257 last to last week I made quite some profit closing my long position and then I did a huge mistake to think that $255 was the highest and I expected it to go down from here was fool enough to put everything in it, opened short position on $250, since then I saw few ups and down and at one point it even went down to $242 but I didn't close the position, became greedy

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And now here I am looking at over $500 loss on my short position although I am happy that bitcoin is rising (don't get me wrong fellas) but I know I ain't having any fun.
So, the question is how long I can hold on to this short position because I still don't want to loose hope of bitcoin going down from here but my worry is what if Bitfinex decided to close my position because I hold them for long? is that possible, I didn't bought these swaps myself, I let system choose best offer for me, are they for 30 days or there is no limit ?
There's no time limit on how long a position can stay open, only a limit on how much of a loss you can build up before you're liquidated to pay off what you owe to your swap providers. That's listed in the interface as a "Liquidation Price".
If/when your swaps expire, more will be taken automatically at the best rate available. Or if you happen to see particularly low-rate ones before then, you can take new swaps manually and close the old ones.
(Edit) Appears I was beaten to it.