Feelings and toughts

I have 2 questions:
1 When I allow myself to feel the feeling, what is the expected end point of the process: should the feeling completely resolve? should I learn how to live with it?
2 I have difficult relationship with my mother and I want to improve them. In many problematic situations (circumstances)related to my Mom, I start experiencing feelings (despair, disappointment) immediately after I face the circumstance. I can not identify what thoughts lead to the feelings no matter how hard I try. Is there any suggestion on how to find these thoughts.