Mary Kay... I did read your rant through to the end and I can fully understand what you are feeling. My first 1/2 marathon was in the 30's, rain and wind gusting in the 20's and 30 mph. When things do not go your way, it can be easy to be discouraged and want to give up.
Just a couple of thoughts for you for the future runs you have coming up:
1) If you are getting discouraged, find someone to talk to doing your pace. They can sometimes bring you back up and encourage you till the end. I had this in the run listed above. By talking with him it was easy to forget the torture going on with my body and we kept together until about 1 -2 miles till the end. He took off to meet his goal, but I was grateful for the assistance.
2) If need be, stop, bend over and just stretch and focus on your breathing. It can help.
3) Your friend is right.... it is just a bump in the road. We have all had bad races. It is all on how you respond after that - do you wallow in the disappointment and not run again or do you learn from the experience and use it to make you stronger. I am thinking of a NYC marathon I watched a couple of years ago - one of the runners used to be one of the best (cannot remember his name). He was in the lead pack for most of the race - but you could tell he was having problems. His form was off and you could tell he was cramping up. He did pull out of the race and the commentators figured his career was over. However, he learned and was going to try and join his country's Olympic team.
4) It sounds like you know where your problems were in the race and you know how to improve in the future. I would suggest if you are not doing it already, keep a log with your runs, races. write down what you did good and what you did not so well. As you go along, you can use it to review and remind you where you have been and how much you have improved as well as things to remember for races.
As a side note, I am curious to hear how your Flying Pig race goes. I am originally from Ohio and have wanted to do either the 1/2 or the full sometime - but since it is when the kids are in school - I will have to wait for a while. Just keep working towards the race and you should have a good one 
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As for me, I had not planned properly today. I was rushing to get the kids out that I forgot to eat before heading to the gym for my aerobics class. I was supposed to do it and a 30 min job. Instead I did low impact on the aerobics instead the high impact version and then only did a 20 min run (1.95 miles) on the treadmill. Tomorrow, I will do a run outside with the wife off for the day. This Saturday, I am going to adjust my schedule and run late in the day so I can volunteer at the Chambersburg 1/2 Marathon. It should be fun and keep me motivated for my race 
October Baltimore Running Festival Marathon (also the 2nd part of the MD Double challenge)