Crew's biggest moment of suffering was the separation.
Nobody knew what was going on and what had happened to the others. Imagine getting separated from your friends and ending up in a strange location with no idea what the fate of the others are, and you couldn't do anything to stop it from happening.
I'm talking about Marineford though. Probably should've clarified, but I dont think it is necessarily fair to bunch up Saobody and Marineford as this one big thing, especially considering both Amazon Lily and Impel Down happen in between that.
I already said that the separation was the biggest singular moment.