C.S.
I have a 14 year old son, a 5 year old daughter and a 3 year old daughter. I had the very same fears you do about having another child after my son. My son was 9 when we had McKenna. I remember crying after we brought her home because I was so worried about how my son, Dayne, was going to react. Especially since he had been an only child for 9 years. Honestly, I had a much harder time dealing with it than he did. He was thrilled. The best part about it was he truly could enjoy the experience and understood so much more about why I needed to spend so much time with the baby nursing her and changing her. I let him participate in the whole experience as much as HE wanted to and tried not to force anything upon him. He took the sibling class at the hospital and we went on the hospital tour with him. We made sure we had a plan ready so that when I went into labor, he knew exactly what he would be doing and where he would be. We also made sure he was able to be at the hospital the whole time but he was not in the delivery room. I felt he could enjoy the experience of child birth later in life when he has his own children with his own wife. Not looking at mommy sprawled out on the table.
We truly had a great experience and feel you have nothing to worry about. Go for it!