Thats pretty scary. I have the SAME exact old style used tank, mines a 135. looks identical, it also has no top braces. There are some L brackets screwed on the corners where yours broke on the top. (I didn't put them there)
I made 3 top braces out of 2 x 4s to keep the tank from bowing and it was recently resealed. Hopefully mine does not share the same fate..
Sorry about the loss, glad your fish are okay