Welcome to the forums! I love the name, btw.
First of all, I'd want to start by telling you I found your story very touching. I never met my biological father. I'm 27, married with a little boy and another on the way.
I was raised by another man, who treated me as if I were his own and I will always call him Dad.
I found out he wasn't my real father when I was 13 years old. James (bio father) also left my mother when he found out she was pregnant with me. They were both young and he did what many boys did in a panic.
I have a sister from James who worked very hard to get in touch with me - she finally contacted me three years ago. The part that irks me is that once in a while she'll say, "Dad says hi and he'd love for you to talk to him."
Not once has he asked my mother (whom he bumps into quite a bit lately) for my address, e-mail, phone number, etc. He actually only tells her that he'd like for me to call him sometime, in a very small-talk-didn't-mean-it-but-felt-I-had-to-say-it kind of way.
So, ZigZagJon, I applaud you for actually wanting to take that step and reach out to her. I hope very much that she will consider your efforts and treat you kindly.
I think the best way to make that first contact with her should be in a very non-threatening way. A letter or an e-mail would be a good way because any contact you make might or might not surprise her. This kind of surprise might result in a bad reaction or a good one -- either way, you'll want her to have time to absorb it all before responding.
Please be aware that she might respond angrily. Girls always desire to have a dad, growing up. Fathers teach us what to look for in men. With my situation, I felt unwanted by my real father and as if I were no good. My dad (the one who raised me) treated me like a princess but he beat the crap out of my mom. So I didn't get to learn nice lessons about men. Your daughter may or may not blame you for some of her mistakes in relationships. She might still be hurt from your betrayal. I pray that if this is the case, that she will overcome her anger and accept your presence in her life. I sometimes think about my real father and there's always a teeny bit of a wish that he would want me in his life.
Another circumstance might be that she might have accepted your nonexistence long ago and may seem indifferent to it now. If this is the case, your appearance in her life might confuse her.
OR she might by overwhelmed with joy that you have decided to seek her.
I know I'm not much help. The only thing I can suggest is to contact her through writing so that she has time to collect her thoughts and feelings.
I wish you all the best in contacting her and I truly applaud you for doing this.