So... I put a stop a 2.8
Then the huge selloff happened, and my actual buys happened at 2.5 for a MASSIVE loss.
How I prevent stuff like that from happening again?
Unfortunately, technically you can't do anything to prevent things like this. You simply can't sell at any higher price during the sell off. And you can't give up selling either, because the price will dip further.
It rarely happens, most slippage is within the spread, but when bad things happen, we can't do anything about it.
Simply use less leverage, and distribute your stop orders in different price ranges to survive market manipulation.