Posting in chat as it is potentially a little outing and I want this to disappear, but also because I desperately need advice from people outside of this situation, because I simply cannot get my head around how I feel! 
To cut a very, very long story short I have been looking for my biological father since I was a teenager (am 40 now), and a week ago I finally found him. In the excitement - and perhaps without sitting and thinking it through enough, I sent him a brief message, telling him about myself and leaving my email in case he ever wanted to get in touch.
Well, he did the same day and was completely and totally overjoyed! Beyond himself really, when I had fully prepared myself to be told he wanted nothing to do with me or ignored completely. However now I feel things are moving much too fast - we have now spoken on the phone and he is so happy and sentimental, but now I just feel so detached and disassociated that I want to go back to the way it was before iyswim (although of course I don't think that is true deep down) I am just so completely confused about how I feel - I contacted him at the end of the day!
I can't bring myself to say 'dad' or 'I love you' or any of that, despite him saying those things and I just feel like it is all too overwrought and emotional and I really just want to go to sleep for a month. He is elderly now and I have caused him all of this disruption just to actually be unable to feel anything other than complete detachment, what is wrong with me?? My reflection seems weird to me now I know what he looks like, and I got so used to just belonging to my mother, does that make any sense at all? Am I just being overly dramatic?
Can someone please help me make sense of why I feel like this, does anyone have any advice?