Well, I did finish it. I really slowed down at the end. My problem was, my story had ended before I hit 50K words. I kept going back through it and adding a little here, a little there, and finally I was within 800 words-- so I dropped a time traveling alien into the middle. Literally into the middle. (My husband read it and said "The time traveling alien has to go.")
It felt like cheating, but oh well, I made it! 
I actually posted my first draft here. If you have the patience & time to read it, feel free to give feedback (positive or negative). I have plans to completely re-work Part II. My husband has given me several suggestions where he thinks I need more, and so I think it'll end up longer than 50K even without the alien. (It's a fantasy story. The alien really doesn't belong!)
I do plan to work on it more. I sort of wanted to do that right away but I made myself wait. I'm making myself wait until the break, at least, if not after, but I'll probably start back on it after we're done traveling.
2009 Trek 7.2FX WSD, brooks Champion Flyer S, commuter bike