Wiped out after century

Congrats on the century first off. Second the way you're describing how you feel post ride sounds like it has to do a lot with your lack of nutrition / hydration during the ride. It sounds like your gas tank was on E and you should have taken on more calories/ liquids. To the other part of your question I think you are fine for the half especially if you're doing century rides now. I never went over 62 for either of my halfs. I suggest shorter rides (50 -60 for your long ride) with more speed / effort. The savings in time will also give you more time to run and swim! Best of luck

Have you worked up to that distance it just did it cold turkey?

If you have not been riding a bunch and done a couple of 60-80 mile rides than then yes you should expect to be wiped out doing a century.

I did a Century this past Saturday, and I never trained past 40 miles. Now with that said. I did train up to 48 miles before mile HIM in April, which i peaked my longest distance ever at 56miles for the race. I felt tired but by no means was I wiped out Saturday for the ride. The total ride for me was 105.5 and with winds picking up plus 4400ft of climbing overall, and a huge climb at mile 80(ugh)I still felt okay at the end. The ride was just a hair under 7 hrs with about 4 stops total. Total time for the day was 10hrs. I ended up a beer and food pairing charity event that evening.

I suspect it has to do with the training and the course ridden, but I have felt wiped out for a lot of my training days the past 10 months. To that point I was sometimes second guessing whether I could go further. I took more rest days where I needed them, and focused a lot on nutrition during training and races. I'm still slow, but I don't feel as wiped out on most of my training days now.

Keep building and it will feel easier even though it's tough. Make sure your sleeping more the longer you go.

Sound like you need a plan. A century is awfully long training ride for a 70.3. You might look at the Be Iron Fit for half plan. My husband used the intermediate plan for his first. It seemed almost too easy, but the mileage built and he finished in 6:18 ish I believe. Not bad for an asthmatic with no endurance background.