How do I cure these devastating garden diseases?

[Gman]

I have a little problem with my garden. The fruits on my tomato plants are rotting from the bottom and the leaves are curling up. The bottom of the tomatoes are black and some have little tiny parasites that look like tiny scorpions. I suspect it's blossom end rot. My peas are turning yellow and dying going from the root up. Lastly, my cucumbers are dying in a very similar way to the peas. Please help me recognize these diseases and how to cure them.