If your argument is that you didn't want kids and have intention of being in their lives, you're out of luck. The law doesn't care about what your intentions and feelings are, and it's not even about what's 'fair' between the parents. The child support laws are predominantly aimed at ensuring there is sufficient maintenance available for the support of the child's needs. In practice, that goes a little screwy; but that's the law for you.
This may not resonate with you (at least, maybe not right now), but:
- So long as you actually are the father, then you need to accept the responsibility for your actions which resulted in the birth of a child; and
- Everything else aside, it is not the child's fault in any way, shape or form. They are the only blameless one in this situation. Whatever you feel for the mother, don't transfer that to the child.