The reason the patch should have been on the inside of the tank is for the simple reason to stop the water if a leak starts.
Obviously, with the patch on the outside of the crack, the water can go through the crack and out the side of where it exits the glass.
Sorry.
I made the same mistake years ago, you only do it once.
And glue, silicon, that is used in aquariums, would have been ok to use, and use under water too, while the fish are insitu.
Just make sure that the patch can touch the glass on the edge where the crack runs from.
This is done by making sure that the gullet of glue, run up the corner of the tank, is removed cleanly, and it is then replaced with the patch with the silicon on it.