A local gas attendent put GASOLINE in my vehicle

A local gas attendent put GASOLINE in my vehicle. It is a one-owner and has been VERY WELL maintained. We even have a life time oil change agreement on it. Anyhow, we didn't know and drove it about 15-20 minutes then parked it overnight at my home. It was running rough but I thought perhaps it was the change in the fuel mix since the seasons are changing. Next morning I started it fine. White smoke out of exhaust. Never seen before. Make it about 4-5 blocks and loss of power with huge billows of white smoke. Thinking perhaps water in line. Let out water. Get back in car and restart. Still huge billows of white smoke. My children tell me water is still coming out. I don't believe them because I know I closed the release valve. Still no power. Lots on pinging and shaking upon acceleration. Car is towed. Five days later (due to weekend and a Monday holiday) mechanic calls me and asks where I purchased fuel last. I tell him without hesitation. Same place for many, many years. He tells me tank is full of gas and explains that what I thought to be water was actually gas. Tells me gas is now spurting profusely from under intake manifold, and running down his driveway. (He turned off motor quickly.) So, is it fixable? I'm concerned that if I repair "it" that there will still be lots of hidden damage. Pistons, injectors, chamber, etc. And that the life of the motor has been reduced. Less than a month earlier I had just spent nearly $5000 on nearly rebuilding the engine, the fuel system, and more. We've been looking for other diesel 15 passenger vans (would need the heavy duty tranny again) but haven't been able to locate anything and I'm afraid with a used one I'll be replacing my baby with a "problem child." So, do we repair it? Would requiring a remanufactured engine be better and eliminate the risk of hidden damage and a prematurely useless engine.