I was certain at the time I invested at the right time and now I am looking at a big drop and feeling the effects of that.
How to put this delicately... if a 20% drop is "big" then perhaps the certainty wasn't very certain? I mean many here hold coins they didn't sell at $69k, which is not much different from having bought at that price.
Presumably your investment horizon is longer that a couple of months so you should just forget about the price and stop checking it every day if that affects your mood.