I spent the last two nights in the Florida Everglades. It was pretty relaxing. Friday night my wife and I were sitting by the campfire watching stars. My wife said one star, which was the brightest one I could see, was talking to her. We continued our sky-watching and about fifteen minutes later the "star" starting phasing in and out. It went from being super bright and then would get dimmer and dimmer until it was gone. Then it would get brighter and brighter again until it was the brightest star. It repeated this pattern for about ten minutes. The sky was pretty clear. There were plenty of stars in the sky and this was the only one that did this. It would go from super bright to gone in about 8 seconds. It would then take about 12 seconds to go from dark to super bright. After ten minutes it completely stopped this pulsating and remained bright.

Unfortunately, we both had new phones and hadn't downloaded any star maps. My guess is that that this was Jupiter. It was about 11:15 pm at night. The position of this star was north to south at about the 1:00PM position with 12:00 being directly overhead. From east to west it was about the 10:00 pm position.

Any ideas on what this was? or what could cause this? No other objects in the sky were affected.

Sirius was in about the position you described at 11:15 last night. Sirius is also the brightest star in the sky.

The pulsating is called "scintillation", which is just a fancy word for the twinkling of stars. Stars are much more likely to scintillate than planets, such as Jupiter, because stars are "point-like", while the light from planets is not point-like.

I have seen some stars really twinkle wildly. Arcturus can scintillate several times per second, and flash between a ruddy-orange and blueish-white.