Does someone know an easy way to communicate from one widget to another widget?
Depending on what do you want to do exactly.
You can have reference from one widget in to another widget and then communicate. You can also create event dispatcher in PlayerController/PlayerState, GameMode/GameState. There are tons of ways, it just depends on what do you want to do.
How can i create reference from one widget in to another?
Just create Variable from Widget1 in Widget2. Then you can use Widget2.SetWidget1(Widget1). And Widget2 will have reference to it. Then Widget2 can access all of Widget1’s public functions and variables.