If it's exactly the opposite way, it's because it may be facing 'left' when you made the Sprite. Note: All sprites have default direction facing right.
One way to fix would be to Edit the Sprite, Flip the image horizontally.
--OR--
In the Event Sheet, instead of pointing towards an object. Set Angle and write:
angle(sprite.X, sprite.Y, mouse.X, mouse.Y) + 180
That should solve it.