I remember you from TTC a few years ago. At the time I think we were both WTT #2? Well, a few months after I had #2 (she was 7 months old), I found out we were VERY unexpectedly pregnant with #3. The ONE TIME my OH and I dtd with no protection, and BAM. Positive test. I was absolutely devastated. 3 kids ended up being a huge change for me. I have found it incredibly challenging. Yet for some reason, my husband and I wanted one more... All our friends/family with 4 kids said it wasn't much different from 3. I don't know if that's true as I'm only 12 weeks with #4, but I'm hoping it is! I'm not really sure what my point is, but I guess I'm saying if you are pregnant and decide to keep the baby, we can 4-under-5 buddies!
Seriously though, I hope you get the outcome you want. Having a unexpected pregnancy is very hard, and I totally understand how you're feeling.