How to disable my key on the mouse?

Hi!

I don’t know how do disable my left mouse button!
I create a reloading system, are all done but, when i press “R” my character still can shoot, and this is ■■■■ me off! I tried to ban left mouse button with the branch and Bool variable, but i don’t know what condishen i need… May be exist somthing something that will block left mouse button if i press the “R” key?