MatBell, it sounds like you know why you are having strange feelings after you hang up with your father. From what you have described, it seems like you tiptoe around the elephant in the room: the feeling of being a disappointment and sorrow. I wouldn't be surprised if the feelings that emerge after your conversations with him continue if you don't address with him "the past history swept under the rug" or the feelings caused by that history.

I don't have a relationship with my father. At one point I did try to reach out to him and discuss the past. I wrote down what I wanted to say to him about that history and its impact on me, including the emotional baggage it created. It seemed to help me collect my thoughts and deeply reflect what was bothering me. I hope you and your father find peace. Best of luck and you aren't alone.