I am afraid that the BTC will then go towards 3k or even less. The altcoins will hit it even harder.
I dont know what i should do today, sell all my altcoins?
Obviously, if the stock market crashes again then it will have a ripple effect on crypto, specially Bitcoin. And since almost all altcoins are hook on Bitcoin's price, then definitely it will be another catastrophic day for the rest of crypto's.
Depends on what altcoins are you holding, on the contrary though, if you have funds around, why don't you take advantage of the situation and buy altcoins? Instead of selling them because you are afraid of what's going to happen, why not just be patience and be calm in this shit-storm? Crypto investments is very different, you need to be really mentally tough in times like this.