Unplanned Pregnancy.

I am pregnant with my 4th about 7 weeks. My youngest just turned 1. I feel as if I can't handle another child nor will it be fair on my other children who are 6, almost 3 and a 1 year old. I know when I have the child I'll love it just like the others but I can't help but not want this pregnancy as everything is perfect in our life at the moment. I feel terrible as so many couples out there would kill for a baby and here I am not wanting this 1. I have tossed up the idea of abortion but I don't think I can actually go through with it. I know we should have been more responsible I was on the mini pill as I still breastfeed my 1 year old. Confused!!!!