Maybe try this:
add the bullet behavior to your object (which may very well be already the case)
condition : If object on collision with black hole -> set angle toward Position of black hole (X/0.5*blackhole.width ; Y/0.5*blackhole.heigth)
to prevent the mechanism of following the Player to kick back in you can maybe add a variable to check if the instance has collided with the black hole and well...stop this mechanism if this variable is true...
If you want to destroy the object in the middle of the black hole you can check if the coordinates of the object match the blackhole coordinates as above.
Can you describe the mechanism wich is used to track the Player further? (since you probably can use the same mechanism to track the middle of the black hole)