Does using ethereum fork will help me here?
Or there is any guide to do this?
It mostly depends on what is X or Y. What these events are in the real life? Today's temperature? The result of elections? Something else? Or there is any guide to do this?
You need to understand that the events of the smart contracts are connected to the blockchain of Ethereum. Every event should be mathematically implemented.
Also, is the events require public permissionless blockchain, public permissioned blockchain or other's system/solution already works well with this event?
But the real problem/question is how to verify X or Y really happen in public permissionless such as Ethereum without rely to 3rd party too much?