"I can't explain why I blew my refeed so badly - I knew better."
I think most of us who have fasted a few times have badly blown a refeed, despite knowing better. You do it once- I probably don't need to say any more than that! It can be a horrible experience... and then you realise why there is a STRICT PROCEDURE for breaking the fast, and make sure you follow it as best you can.
I'm big on self-discipline; very important when staying on a healthy restrictive diet. Good for lots of things! Ok, so what are the biggies? Kelly McGonigal talks about some of the issues, in a couple of links I posted under the heading 'Willpower videos', further down the page. Her book, Maximum Willpower is also very good. The most important factors are sufficient sleep, eating, also exercise plays a big factor, and mindfulness meditation. I also found personally that Water Fasting greatly helped my willpower to the point where I was able to quit a destructive drinking and smoking habit. So you're definitely doing the right thing.
On your breaking of the previous fast, I think I might have added a comment, but I forget what I said now. I think sometimes you do have to break a fast before you might wish to, and there are so many factors to this. Here's something I chanced upon last night by Dr Isobelle Moseley-
"If there is any one vital rule of fasting, one never should fast over strong, personal protest. Anytime you're fasting and you really desire to quit, you probably should."