OMG! You sound so much like me! I was born with a black thumb and have fought like hell to turn it brown...edging towards green. If you ever want to try your hand at gardening again I've got a few suggestions that may help in this insanely dry desert environment....
1 - The book "Extreme Gardening" by Dave Owens. I learned a lot from this guy and managed to make a few tweaks that have proven relatively successful.
2 - Big galvanized water troughs used for cattle. These are my raised beds. I know the metal sides can get really, really hot in the summer, but I wrapped one of mine with a recycled grass shade screen that my neighbor was throwing out, and another with that flimsy silver insulation stuff you can buy from the home improvement store. Both methods worked wonders at keeping the temp down.
3 - Fill those troughs with a combination of compost, potting soil and coconut coir. The soil and compost provide all the nutrients....but the coconut coir...even a little of it...works wonders at retaining water for the plants to utilize and substantially cuts down the amount of water you need to use. I used the coarse coir in the troughs/beds and the fine for starting seedlings. (It also works great as animal bedding...but it's rather expensive for that.)
4 - Whenever you plant something, cover the surface of the soil around the plant with mulch, straw, or coarse coconut coir to help retain the moisture in the soil and keep the temperature down.
5 - And finally...shade cloth....lots and lots of shade cloth.
I've also found a very few crops that grow exceedingly well in the extreme heat...like Armenian cucumbers and Egyptian spinach. My cucumbers were over a foot long and 2-3 inches in diameter and grew in full sun.