You need just follow the main rule of investment in cryptocurrency: You have lost you money by buying any coin. And also you don't need to hold all the eggs in one basket! Life will be easier if you follow this simple rules.
Yeah, Diversified your investment to minimize the risk if other currency will dump and you may recover your lose to other coins. This is a good advice which I think applicable at any market situation. You just need to invest on those project with good reputation.
Yeah it is good idea you can split your investment in different coins and you may be able to recover your deficits in rising coins. But dont even think of quitting crypto market. The money you lost will never be recovered. You should stay here and try to trade in affective way so that you return your lost money. It is important for your trust in cryptocurrency.