Sorry to hear that…

Your mounting installation of your engine is not a safe. The load on your mounting block is not shearing or either bearing but torque. The distance from the engine to the base and the static thrust of your engine is big enough to fold or vibrate hard at maximum power, you need a support member from the engine's center of thrust to the base to serve as a compression and tension brace, also on the side. The good thing you have good anchoring on the bottom. Again sorry, I feel bad for what happened.

Next time look for backup or fail-safe like an extension link rod as an emergency shutdown or fuel cut-off for your engine.