Dear Stung----I don't know if this applies to your situation at all.....but, I can remember some situations in my life where I had built up some strong resentments against another person---feeling very strongly that they were the "bad" one and I was the "good" one.
Then, if that person did something nice or generous toward me---I felt oddly uncomfortable of responding with gratitude--like I was angry that they had poked a hole in my strong image of them as completely and thoroughly "bad".
(If I hate you...for God's sake don't do anything that might make me like you)....LOL.
dandylion