if I am not married and have my child 50% of the time would I have to pay child support

If a court orders you to, yes.

Good answer, Erik. And, I agree.

But, don't let it get that far. Go to court now and under the equitable considerations that a court considers, you should raise all of the facts that you have discussed here. It is possible that you might convince a court to reduce your liability. Don't do it yourself. Retain an experienced family law attorney. Trust me on this. Attorneys who go to family court regularly know what arguments work and what arguments simply blow up in your face, doing more harm than good. And, a bad day in court can make your life miserable forever and a day.

Bottom line: the reason that Erik's answer is correct is that it is not about you and the fiance and what she did or what you did or how she feels or how you feel. In the family and divorce courts it is not about you two. The only consideration here is what is in the best interest of the child.

That is all.

This answer is provided for informational purposes only. True legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction and with experience in the area of law in which your concern lies.