Roofing is a thank-less job?

My wife asked me to help redo her mom's roof. I rolled up with my brother-in-law in tow. When we got there, it was only her cousin and uncle - so 4 of us had to tear off, and re-roof the entire thing. We got started and got about 1/2 done on day 1. 2 of the 4 bailed on Sunday so it was me and her cousin who ended up getting this thing 80% done. The cost was about $1600-my wife and I fronted all but $150 that her sister paid for materials. Her mom had indicated that she would put up $300 for the roof - when it came time to pay, she said she would have to make payments. Everyone was "free labor." I got sun burnt, could barely function Saturday night from fatigure, gave up my weekend, was sore for 3 days afterwards, and for what, so my mother-in-law didn't even have the decency to thank me? I didn't say anything to my wife until like Tuesday. Should I be mad that I couldn't even get a thank-you? I guess she was entitled to a free roof. I'm done helping out there.