I am sad you will remain unborn, and sadder still that it was the right decision. In case their is an afterlife and your soul had been formed, I'd like to try and explain what happened in the hopes you can forgive me one day and we can get to know each other.
First, I'm going to start off with what I know and believe in order to give you a frame of reference. I'm not sure what the afterlife holds, or even if there is one. What you know about the nature of human existence may be vastly different than what I know/think I know and what I believe.
The Biology: Our current understanding is that we have a pretty good idea of the biology of your existence. Children are formed within the body of a woman after the man's emission fertilizes the woman's egg.
The Behavioral: This can happen with a man and woman that feel great emotion for each other, but can also happen if they don't know each other. This can happen when a man forces himself on a woman (whether he knows her or not), and can also happen when medical professionals store the emission of the man and fertilize the woman's egg with it using tools. In your case, I felt great emotion for your mother and she gave me every indication she felt the same.
This can happen on "accident", on purpose, or purposefully on accident. I but the first accident in quotes because what people call accidents usually aren't accidents. Most "accidents" are people behaving irrationally under the assault of floods of hormones. I'm not sure it's been proven, but this is likely a biological trait more than a behavior. I guess the behavior part comes in with the excuses we give our rational mind in order to believe we weren't conscious of the risk of pregnancy.
The Spiritual: We're absolutely clueless on this part. First, we don't even know for sure we have a soul - that we are more than the sum of our parts. Since if you're reading this we obviously are, I'll assume we do. We also don't whether we have always existed and inhabit our bodies or spring into existence in the womb. We don't know if our souls continue to exist after we die. Assuming we do, we don't know if we meld into a collective entity/intelligence or remain separate individual beings. Assuming the latter, we don't know what happens to us after our body dies. There are as many guesses as we can imagine, and we often kill each other because we disagree on the subject.
We also don't know when the soul comes to inhabit the body. We have a lot of arguments about abortion over that uncertainty (but to be politically correct, we pretend we're arguing about when 'life begins' not when a person becomes a person/soul and body join or are formed).
The Social: This gets insanely complicated to apply to all of humanity, so I'll just stick with your specific situation. The society in which your mother and I live is one arising from centuries of believing a specific guess as to "what happens to your soul after you die." 'Religion' is a term that is much more elaborate than just "what happens to your soul after you die," but almost always includes a version of "what happens..." - so I'll be using it for "what happens..."
Anyway, the Religion and it's variants that have dominated the societal culture your mother and I live in isn't the most pleasant. For (I'm embarrassed to say) thousands of years, we've operated believing that a soul in a man's body was superior than a soul in a woman's body - treating the woman like property (and worse) was the norm for WAY too long. This is ironic to me, as the biggest two religions of our time both essentially instruct to "imagine that you had lived the life of the person you're about to interact with, and treat them like that."
My understanding is that the Christian version is "love thy neighbor as thyself" "treat others as you want to be treated." The actual Christian's will probably see it in their best interest to disagree, but from the way that Jesus guy talked in other places, I think he meant to go overboard with it. Don't just be nice to people you run into, but go out of your way to be nice. I mean, he brought thieves and such home for dinner after all.
The Muslim version is apparently "As you would have people do to you, do to them; and what you dislike to be done to you, don't do to them." I've also noted that Surah 16 kinda sounds like 'don't be disappointed if you have a girl' - but I've seen documentaries that indicate that's not how it's being practiced.
Somehow, though, women were treated like property and worse for a long long time. There was this thing called 'marriage' to glorify the moment in time when the woman went from being her father's property to her husband's property. It's gotten a little bit better since then, but a lot of our laws are derived from that viewpoint. As it turns out, your mother hadn't gotten the divorce finalized yet, and by the laws we were living under you would have legally been the child of her husband.
I'm not sure exactly how much that actually influenced her decision, but it was the main reason cited. I really didn't want her to get an abortion. I thought I was in love with her though, so I decided to support her decision.
The decision really had nothing to do with you though. We didn't know you. That we never will is what we get to bear until we find out what's on the other side. I hope you understand. I'm sorry. I hope we get to know each other one day.