Mouse follow help

I have a 2D object with the camera following from above, my issue is I want the object's (a spaceship) nose to follow the position of the mouse while the right mouse button is held down. I cannot for the life of me get any of the suggested c# code to work I've found for other peoples requests. I've come close on a couple but ultimately the ship either flies up up and away off the game board, or the nose points directly up (the Y plane).

Basically, it's a 2D top down space shooter kinda like Asteroids in which the WASD key's move the ship around on the X plane and when the right mouse key is pressed down makes the ship's nose rotate towards that direction.

Any help would be greatly appreciated!