expat and Earlybird have both given excellent comments here.
How pg are you? Can you really imagine yourself feeling like this for the rest of the pg? Don't you think as time goes on and you feel the baby growing you will have loving thoughts and excitement about it? I cannot imagine spending 9mths worrying that its "wrong" and i bet you won't either.
I think fate is a wonderful thing. I fell "accidently" with dd but was thrilled, just couldn't have been worse timing as dp had been redundant and we had no money. But fate gave us a lovely daughter who had made our lives wondeful.
Now i desperately would like another child and hey presto my body has stopped having periods (no i'm not pg). currently awaiting some test results.
But i know i'm lucky to have one child.
Soo many people have trouble conceiving and would give anything to "accidently" fall pregnant. That should make you feel priviledged to have been able to create another beautiful edition, that should tell you its meant to be and the fact that you have a loving environment to bring this child up in means its meant to be.
I am not anti-abortion, i do realise there are times when its appropriate. But knowing the little info from your thread, the above is my opinion on your situation.
There have been a few threads like this recently, and all i ever think is how must this make those women who are having fertility problems feel?