I think the core problem is YOU lost belief in your product. It is very common for successful companies to have key founders quit before payday and during shit

I think the core problem is YOU lost belief in your product. It is very common for successful companies to have key founders quit before payday and during shitty times. The company lives through the tough times. What has served me well is to have an attitude that I am going to go along on this ride(my startup) regardless of my cofounders. Until you can sustain that belief, your start-up will live on(hopefully with your co-founders--but not necessarily).