Learning to Breathe

I ran 26km yesterday. And my legs are still sore. This is the time I've really been sore like this the day after a training run. But it was a hard run. I know after my 23k last week I was hoping that if I took it easy this past week (which, for the record, I did) I would feel energized for the 26k. Unfortunately, that was not the case. I started out feeling great, but by 10k, I was beginning to feel a little sore, by the 15k mark I was just tired. The last 7k were horrible. I thought I wasn't going to make it home just out of sheer exhaustion. My legs were doing me in, they were so sore and tired (probably from water skiing for the first time in 4 years at a cottage 2 days before the run) that just willing myself to keep putting one foot in front of the other was brutal. However, despite all of this, I did finish my run. On the downside, it was so physically and mentally exhausting that I kind of (and I'm not proud to admit this) burst into tears as soon as I walked in my front door, and then I was out of commission for the rest of the day.
So now here comes my dilemma...
My goal has been to stick religiously to the training schedule, which has been tough, but I've been doing pretty well with. BUT with my crazy busy work schedule I've been burning myself out. Waking tired, running, working out in the sun all day, and just being utterly exhausted by 8 or 9pm. Because of this exhaustion, my long runs have been suffering.
I'm toying with the idea of cutting back on my training, or at least cutting a run from my schedule (so I would run 4, instead of 5 times a week), or maybe fitting my run in later in the day so I'm not waking up at 6am to run before work. This week I'm going to experiment a little, and we'll see how that effects my 29k I have to do next Saturday.
Also, some cooler weather would help. I think this extreme heat and humidity is playing a factor in all of this.
So wish me luck! Hopefully my experimentation with my training will pay off and my next run won't be quite as exhausting.