All good! I think just heat stress.* Cut it back about one-third, above existing leaves, leaving plenty of foliage on the plant. I know it will hurt to do that, but it should grow back pretty quickly. If any of the stalks are clearly dead -- brown and shriveled from top to bottom -- cut them out. If you're not sure, cut them back to just above the third leaf node. If it is still blazing hot, see if you can give it a bit of afternoon shade. Water well, making sure the entire root ball is dampened and water runs out of the bottom holes in the pot. It does have holes, right? Don't use a saucer.
When you fertilize, water the plant first, then mix the fertilizer one-third to half-strength and feed every week, rather than full-strength every two weeks. Full-strength in pots in the heat stresses the plant. It should revive soon. Enjoy!
*There is only one other thing. I can't see them in the photos, but watch for Tobacco budworms. They like calibrachoas, petunias and geraniums and can ruin the plants. The first sign is that the buds get chewed and don't open. When they are young they are very hard to spot. Google it...tons of info and pictures on the web. Hand-picking, insecticidal soap spray can help.
