The long run that never happened

I am seriously bummed!  I have 18 days until my marathon and I have not done a run longer than 18 miles.  The last long run was a week and a half ago.  I really want to hit the 20 mile mark but I have a few obstacles.

Last night I was googling long runs and stuff and kept finding information that says you shouldn't do a long run a month before the marathon.  But in my head, I need to do one.  This marathon thing is a head game and in my head, I need to run.  I haven't been exactly burning up the pavement during the week, so...

I prayed really quickly and asked God for wisdom, but not really thinking much more about it.  I went to bed and got ready to get up at 3 am to go run before Mark had to go to work.  I didn't sleep much last night.  Sign from above?  Then after the alarm went off, I got ready and started my run.  I was REALLY slow!  But my new water backpack was leaking. I figured it would stop leaking in a bit.  But by mile 4 when my pants and shirt were SOAKED I realized that it wasn't going to stop and I would chafe and not have any water to drink.  So I came home.  Sign from above?

I am feeling like a failure and I am totally scared about this marathon.  It is all I can think about and stress about.  Should I try and run tomorrow?  The day isn't nearly as "perfect" as today was.  Plus, my dead toenail hurts.  

I know this sounds stupid and like a "pat" answer - but I am going to start praying about this.  I need to get my brain in the right direction and will it take 20 miles to get it there?  I hope God has an obvious answer for this!!

UPDATE: God is good.  As I wrote that last paragraph, I doubted (gee anyone surprised) that God would really give me an answer - and that I would actually hear it loud and clearn.  But my doubt does not stop God from loving me - actually, nothing can stop God from loving me, even though I'm sure I push His buttons!  Anyway, my husband works with someone who ran marathons.  Mark called me and had me speak with Rod.  He assured me that I'm ready and that a long run would only HURT me.  I feel better and since God knows how thick headed I am, He even gave me peace!  Thank you Lord!!!!!