First, I am no expert and my experience is only my own and therefore anecdotal.
I have had this exact problem every year for the last three years with my tomatoes. I believe the problem started because I bought Tomato plants from the store that were already exposed to bacteria/spores and then infected my garden.
Here is what I have learned trying to fight this problem:
The fungus quickly spread to every garden space including spots that were separated by over 100 feet and ten feet in elevation. So once you get it, you've got it. Everywhere.
I have used expensive copper-based fungicides to little effect other than the shrinking of my pocket book. I have also created my own Bordeaux mix, cornmeal and milk, and Neem oil. The Bordeaux mix and Neem oil, so far, have not prevented anything. They appear to slow things down and even halt the spread of the blight but if you don't spray at just the right intervals then it spreads. And the blight knocks the blooms off the plant. What good is saving a plant that can't hold blooms?
I have never had it spread to my peppers. Sweet or hot. Or my egg plants. Doesn't mean it can't, just that it hasn't yet.
The fungus has a heat range it prefers. I can get an early crop of tomatoes in before it knocks the blossoms off. Then during late spring and summer I just try to keep the plants alive and then when it cools off, the surviving plants start producing again. It's a hardworn effort with marginal reward.
My heirlooms fair worse. But Celebrity plants don't do much better. So much for their fabled disease resistance. I have found no disease resistant variety yet that is hardy enough to solve my problem, even a little.
Finally, the only time I haven't had problems was four years ago. Back then I put down freshly made cedar mulch that I had left over from reducing some cedar branches in my woodchipper. I am going to try this again this year. The mulch helps hold moister in the ground so less watering and less opportunity to splash spores up on leaves. More important, I am hoping the mulch will be an inoculation barrier. To keep the infected soil sealed off. Cedar has a natural fungicide in it which is why you can't use the wood for growing mushrooms. I am hoping that this property will make it an unsuitable bed for spores.
This has been the most frustrating gardening problem I have ever had. My best advice to anyone reading this is to not buy plants from the store. The plants and soil may be from several states away and introduce diseases to your soil. Seeds can also be infected but most seeds are treated with a fungicide so it is less likely.