Glad to hear no one was hurt.
Looks like you blew out a wheel cylinder. Not too costly, but the shoes will have to be replaced too.
Go over 100% of your brake system. Pads, shoes, calipers, etc. Any questionable steel lines or hoses get replaced! Fresh fluid all the way around.
Back in 2008, my 1984 Chevy K20 had a seeping line to the rear. $500 in parts and a full weekend's work, the brakes never gave me grief again. Sold it this spring with a clear conscience.
TT 2015 19RD "TheJayco"
TV 2003 F-350 "Montblanc" - Housebroken chore truck
Sitting in The Cheap Seats.
And proud of it!