I think most of your feelings are normal, though for some people it would be less hard to accept. I don't think you are being selfish, and it takes a lot to seek advice when you know that you may come off as sounding that way. It annoys me that some people are so quick to call you selfish, bc we are here to offer advice and support each other, not to judge and name call.
That being said, I think the bigger issue is that he hid it from you. And you bringing up the fact that he has said he didn't want the child...it sounds like he is telling you what he thinks you want to hear, perhaps being a bit manipulative. I date men with children all the time, and I have one of my own so it never bothered me, but that is YOUR choice to make and he took that choice away from you when he hid the child from you. I do agree with Flooded, though...what if you were to get pregnant and things didn't work out? Would he be hiding YOUR child from someone else...running around telling people he doesn't want the kid???
I think a big part of this is also has to do with the child support issue...it is frustrating to feel like he is just a paycheck for his ex gf, and that takes away from what he will be able to provide for you and your future child. Maybe a therapist can help you work some of this out and get down to the real issues here...in the meantime, I would seriously reconsider any thoughts on having a child with him until you get it all worked out and have come to peace with all this. Hugs.