Reminds me of a guy with a truck camper that always told me, no reason for RV antifreeze, just blow the lines out and it will be fine.... He showed up at a group campout two years in a row with a badly leaking toilet and his wife was furious (they had to walk to the campground facilities instead of using the ones in the truck camper). His toilet valve froze and broke, twice. The next year, they had a travel trailer... I think he uses either a better winterizing blow out procedure or uses RV antifreeze now... I laugh out loud when I am winterizing our trailer and get to the toilet, it has been a number of years and it still reminds me of that guy being so stubborn.
Not saying yours was caused by freezing, yours sounds like it is caused by stress with the plumbing. Hopefully you can make some changes and eliminate the stress (and add a shutoff to help in case of future problems).
