Emotional reasoning involves placing an over-reliance on what you are feeling, sometimes to the extent that you believe that what you are feeling points to the truth even in the face of clear evidence that it is not. An example would be if you feel ashamed or guilty and therefore believe that you must have done something wrong when in fact you have done nothing to be ashamed of.
Don't ignore your feelings (they can be useful pointers to important issues or facts) but at the same time don't assume that your feelings indicate the truth of a situation, particularly if there are explanations as to why you might feel the way that you do which are not as exteme as the conclusions you are drawing.
To check whether your belief are overly guided by your emotions, ask yourself what is the thought going through your head which is leading you to feel that way and then assess whether that thought is justified. Thus for example, if someone tells you You are useless you may think 'I must be useless because they are saying that' then you feel useless and start to hold that as an ingrained belief. You could challenge that thought process by questioning whether there really is evidence to back up the other person's criticism or whether it may actually show more about their controlling/insecure/aggressive personality than about you.
To find out more about tackling negative thinking patterns leading to painful emotions click on the link below:
CBT Techniques to Beat Negative Thinking