Answer: Wow...the pressure's on! I'm a little concerned, because none of the 3 tomato varieties you list is particularly disease-resistant. I'm also concerned that whatever killed Mr. Stripey might spread to your others. (Next year, you might choose to grow at least some varieties that are highly disease-resistant, just for insurance.)
It sounds like you are diligent about watering, but I have to ask: are you sure your plant hasn't suffered from lack of water? Or too much water--saturated soil for prolonged periods can lead to root rot, which leads to wilting. Since the snapdragons have suffered the same fate, a watering problem is still my first guess.
If the plant wilted overnight, and water (too much or too little) is not involved, then I begin to suspect something like a bacterial wilt. A plant infected with bacterial wilt will wilt and die rapidly, with no leaf spotting or yellowing. (This is a key in diagnosis--rapid wilting of a green plant.) Usually, symptoms caused by fungi (ex. fusarium or verticillium) or root problems develop slowly--whereas bacterial wilt symptoms can progress rapidly--even overnight. Bacterial wilt is more common in the south, however.
Bacterial wilt cannot be cured. You should pull the plant and remove it from the garden. Wash anything that came into contact with the plant (gloves, tools) with a 20 percent bleach solution to disinfect them. Practice good garden sanitation practices, especially cleaning up debris at the end of the season.
Now, to your current situation. I really can't say for sure what will happen to your other 12 plants. Curled leaves are not unusual on tomato plants--especially on the lower leaves, and especially in hot weather. (Check the curled leaves to be sure they aren't full of aphids or whiteflies.) Other than that, I think you'll have to wait and see. Try to add compost to your garden plot every year--compost contains lots of beneficial microbes that can minimize pathogen populations. Solarizing your soil by spreading plastic over it can work to reduce microbe populations, but it is usually most effective in the southern part of the country. I would try to build up your soil with compost, try to maintain your tomato plants in optimum health with good nutrition and watering practices, and choose disease-resistant varieties. By planting the same crop year after year, you do invite various diseases to "take hold". Good luck with your crop!
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