No, I wouldn't have an abortion in this situation. 2 of my cousins have become unexpectedly pregnant in the past few years. One was just about to turn 40, and ended up having a shotgun wedding, LOL! She had that child, and then another one a few years later. I couldn't imagine our family without her girls.
My other cousin had 2 older boys and ended up pg again in her 40's as well. Both had their babies and couldn't imagine it any other way. If it happened to me, I'd welcome it since I'd figure that it was meant to be. Frankly, I've always wanted to be an older parent. If for some reason an oops happens in our 30's or 40's, then it happens! I'm now at the age where I'm just fine with letting nature take it's course. In my 20's, I would have been beside myself if I'd gotten pregnant, but I still wouldn't have had an abortion.