yeah i have a wack of livestock, tons of corals.....

I doubt very much that the trim casued this :) It looks like the setup was not level once the water was added, the shifted weight caused the trim to start cracking, and the pressure then transferred to the stand. Unless this is a warranty approved stand, the tank manufacturer will likely not cover it.

id drain it and throw your livestock into whatever you use to mix salt with a powerhead and heater
No way would i keep that

if your using the AGA stand they may cover it but from those pictures it looks way out of level which will probably void any/all warrenty you may/may not have ever had

it WAS level before last night. The tank has been running for a year and a half. I noticed last night that the water was sitting higher on the one side than it ever was before. The breaking trim and shift in weight has cause the whole stand to list to one side by a half an inch.

Its an AGA stand so should be warranty approved. However i can vouch FOR SURE that the tank was level as of yesterday. Because i pay really close attention to that. And seeing the water listing is what first caused me to panic.

Did you check your floor as well??

Brace the stand and or get a new one. Adding 1X1's could work just as well if you have limited space.

Good luck!!