My 14yo daughter's bio dad who abandoned her before birth has now filed a paternity suit

In 2008 when I was in my early 20s, I made the poor decision to briefly date a man I liked as a friend but didn't have romantic interest in. It lasted about a month. A week after I broke up with him, I found out I was pregnant. I told him right away. He seemed to think this meant I would come back to him and we'd raise the child together, but I made it clear to him that this wasn't the case. I gave him the option to co-parent. We continued speaking for a few weeks, but didn't get along, and came to the joint decision that we'd go our separate ways and I'd parent the child myself. He mentioned wanting me to sign something saying I wouldn't pursue him for child support, which I was willing to do, but it never ended up happening.

We didn't speak again until I found out the child's gender, a girl. He was raised as an only child by a single mother, and he seemed to have a harder time with the idea of letting me raise a boy by myself than a girl (barf). But she was a girl, and after I told him that, it was the last I heard from him for a long time.

I already had an older son with my ex, and he and I ended up getting back together when I was pregnant with my daughter. He expressed the desire to parent her from the first moment he learned of her existence. He was in the hospital when she was born, signed her birth certificate, we gave her his last name, and he has been her father her entire life. We're not together anymore and haven't been for many years, but we have a good co-parenting relationship and never had to go to court over it.

When my daughter was 11, I broke the news to her about her biological father and the dad she's always known. It was obviously very shocking to her. I told her that if she was curious about her biological father or wanted to know more or speak to him or anything like that, it was perfectly fine. But she had zero interest then, and still has zero interest now of having anything at all to do with him.

Both myself and my daughter's biological father have continued living in the same area since then (which is in Virginia) and I've always known that he has kept tabs on my social media, although I don't post a lot. About 3 years ago, not long after I told my daughter about him, he contacted me, and I was willing to text with him and tell him a little about her. But I told him that the decision for the two of them to speak and get to know each other belonged solely to her, and that she didn't have any interest so far. When he tried to add her and reach out to her on social media anyway, it upset my daughter, so I blocked him and cut off contact. She blocked him as well, by her own choice.

Yesterday I got a call out of the blue from a guardian ad litem and found out that bio dad filed a paternity suit. He didn't have my address, so I haven't been served yet, but the guardian ad litem got our information from my daughter's school. Right now, it's only a paternity suit, but I'd assume he'd have some kind of further motivation once he's proven to be her biological father. But what kind of rights could he possibly get? He was immediately notified when I found out I was pregnant over 15 years ago, and given the opportunity to parent, which he declined. I didn't take her and run off. He could have done this at any point in the last 14 years (she'll be 15 in the spring), and never did until now. Not only does my daughter not have any interest in speaking to him, but she's never even asked me any questions about him, even though she and I are very close and I have made sure she knows I'm open to it and fine with it if she does. Could they potentially make her speak to him or see him? If he's proven to be her biological father (he will be), will that terminate my ex's rights (the man who helped me raise her all her life)? What kind of rights would that grant bio dad, if any?

I'm sorry if this is all over the place; it's obviously very emotional for us. I've never been to paternity court or custody court so I don't know what I'm in for. I'd appreciate any advice.