How to Blow an Interview Without Trying

I went in and took the interview for the promotion. I thought I was doing pretty well through the first 3/4 of the oral interview. The questions seemed easier than what I thought they were going to be and I tried to think of all the benchmarks they would be looking for in each one. I got a nod at one point saying which I took as you're doing great. And then came question 4. What do you think will be the hardest thing to adjust to by promoting and I started out that learning the policies and dealing with earning respect was not really a concern of mine, I can deal with that, the hardest part would be knowing I'd have to take another shift, (and the tears start to roll) and make my family life hard for 6-8 months until I could possibly get back to first shift. Yep, I broke down in an interview. How awesome is that? I don't have enough stress in my life, so yeah, why not add trying to promote for an extra 300 dollars a month, lose seniority, lose being on first shift for 6 months to a year, lose my baby at nights, add more responsibility, and pray that I'm not stuck working doubles. WTF was I thinking and am actually considering, if they look past the whole crying jag, and offer me a position.