My 6 almost 7 year old son does not want a sibling. What should I do I am pregnant?

I just found out last night that I will be having another baby. My husband and I have talked about it with our son but now that I am finally pregnant we fear we might have made the wrong choice. We have always asked our son how he would feel if he had a brother or sister and his response was always 'I don't want one". I always took it with a grain of salt and didn't think much of it. Well tonight at dinner we were asking him again and I asked why he doesn't want a sibling and his response tonight night was " Because you and Daddy won't love me anymore". Needless to say I was heartbroken and now I am not sure what to do. I am so against abortion so that would not be an option. I have spent the few hours reassuring him but nothing seems to work. We have not told him that I am pregnant and we don't plan to tell anyone until the 2nd trimester. I could really use some help from people who have had the same problem and any advice would be be greatly appreciated