I don’t really know what to say as I have no experience of CSA etc but I’d assume that you don’t have a leg to stand on.
You knew full well that sleeping with her ‘could’ result in pregnancy, and she certainly didn’t take advantage of you. The consent was there from both parties.
All I would say is, you have a child with her, so you deserve to pay accordingly with CSA, she can’t be expected to raise your child with no support financially just because you didn’t want the child.
On that note too, is it fair for your child to be the one to have to come looking for you. If I wasn’t with my boys mum I’d be banging her door down every day to see them – growing up thinking their dad didn’t want them just isn’t an option.
Sorry if it sounds harsh, I wish you well in whatever you choose to do but I’d be wary about coming across like the bad one here, as I don’t think you will be looked upon too favourably by CSA, the mother or more importantly the child.