Hi R.,
First of all...CONGRATULATIONS!!! You've got a real, honest-to-goodness miracle goin' on. Always remember that.
Secondly, I know that you've got to have many different emotions and worries going on right now, and I'll be honest...mood swings during pregnancy are VERY powerful. That being said, do not let ANYONE or ANYTHING take one moment's joy from your pregnancy. Cherish this time, it is amazing. My daughter is almost 1, and I am still blown away by the experience.
I was 23 when I became pregnant, I was 24 when I found out, and this past August marked the first b-day I spent as a mom...a SINGLE mom. I was scared and worried that I couldn't do it. I also became overly preoccupied with not having the "family unit" that children are "supposed" to have.
But you know what? It is AMAZING how becoming a mom puts things in perspective. It also puts you in survival mode. Things you thought you weren't capable of handling or dealing with become victories that rest at your feet. I'm not saying it will be easy, but I am saying it can be done.
Now, you inquired about support groups for single parents. I know of two, one is online, the other is in-person.
The online community I am referring to is located on a site called Babycenter.com. This site isn't just for single parents, though. It's for all parents, and I would strongly encourage you to join (it's free). You can see info about what's safe during pregnancy, concerns you may have, and shows the development of your baby, week by week. There are many different bulletin boards on Babycenter (single parents being one of them).
The "in-person" site is located on Meetup.com (the exact site is: http://singleparents.meetup.com/2/boards/ ). This site is also free, and is aimed towards parents that already have children. It lets parents meet up in different places (some outings with kids, others are just the parents getting out to socialize).
I apologize for bombarding you with so much info...:-) I know what it's like to be in your shoes, and I just wanted you to know that you're not alone, and that you CAN make it.
Take care,
L.