i need advice!! pregnancy! abortion! divorce!

okay well I'm 8 weeks and four days pregnant. my husband wants me to get an abortion. his reasoning is we already have four children, we don't think we could get by financially with five kids. I am so against abortion but I don't want to have this baby and end up getting a divorce from my husband because he doesn't want a fifth child. I don't want a fifth child either but this is our fifth child so whether we like it or not here's the fifth child. if we were to get divorced it would wreck our children completely and I don't want to do that to my children. I'm just not sure what the hell am I supposed to do. yes we were using protection. I had the Mirena iud and it fell out and we got pregnant before we noticed it was missing. any advice would be greatly appreciated.