I've found learning about 'I' statements to be really helpful with respect to distinguishing between my beliefs and reality and my emotions and reality too.

Beliefs can be false to reality, for example whereas reality is true to itself. To see that I'm expressing my beliefs rather than reporting on external reality means that it is possible for me to see things differently (change my beliefs).

Emotions can be responses to the past rather than the present too, for example. Or their intensity can be more a function of the past than the present. To see that I'm expressing my emotions rather than reporting on other peoples intentions means that it is possible for me to conceive of their intentions differently (change my emotions).