I can't believe it! Number 4 on the way!

We just had our 3rd child a girl she is 5 months old and I find out today I'm pregnant! I'm excited yes, but I'm nervous having two so close together, I am also nervous what people will say that we shouldn't have four kids that were way in over our heads! When should I start telling people, I usually am too excited to hold it in and I tell people, but my husband wants to wait. I also just went back to work I'm sure they aren't going to be happy me having another baby. I am so nervous but excited! Anyone else going through something similar? I would love some advice please!