I'm thinking it is more than pure coincident that she appeared in your doorstep just days before she found out she was pregnant. I don't see this ending up nicely. Point her to the nearest women's shelter or crisis pregnancy center.

I'm also going to guess that this is not the first time your "best friend" had abused your kindness and friendship, right?

you're not responsible ... she needs to get a job to look for a place to stay she can't rely on you
not only is she putting pressure on your relationsip but also acts like she's not bothering at all !!!
give her a time limit

There’s a big difference between a true friend and a user. She’s not going to start appreciating you if you let her stay, and her behavior will only get worse. I speak from my own experience as well as my daughter’s recent room mate problems. There are plenty of programs out there for her to get help. You can’t take on her responsibilities for her. Hope things get better for you soon. Hugs

I've been in your shoes a couple times and learned the hard way. I let my cousin move in with me and originally told her to just pay me $150/month to help with her share of the utility expenses. She gave me a sob story about how she couldn't afford it. I also couldn't afford to provide for her. But I made an exception and told her I'd let her stay if she would clean the house. She lived with me for around 6 months and NEVER cleaned a single thing the entire time. When I tried to get her to help, she made excuses. She even pretended not to know how to use a vacuum cleaner! I then got so frustrated, when I saw my gas bill had tripled, that I asked her for $100 to help cover a small portion of the increase in utilities since she lived there. She got very angry. In the meantime, while pretending to be so broke and incompetent that she couldn't help out in any way, she was purchasing a new flat panel tv, gaming system, going for weekly massages, had a gym membership, etc. She brought some strange man, whom she had JUST met online, into my house on the very first night she moved in and allowed him to sleep over without ever asking if this was ok.

Long story short, she was an extremely manipulative, entitled, evil person. I no longer have any contact with her. And I will never make the mistake of feeling sorry for someone and allowing them to use me like this again.

Kick your friend out. Give her 2 weeks to figure out what she's doing and where she's going. That's it. That's more than enough. She's not your responsibility. She's an adult.

I agree to give her a 30 day notice that she has to leave..... Her baby has a father and I imagine that she has a family..... This is no good for any of you... If more is required of her she may require more of herself..... Don't take on any guilt trip over this...... She's an adult....... Big hug..... xo

IT is not your responsibility to take care of her or the baby. She is an adult, she made this child and now she has to face the consequences.
If you make it known that you are taking on her problems, you will actually be enabling her not to grow up, which is actually a disservice to her and you can say this to her in kinder terms.
If you keep her in the house, the bf will leave.
I m not the example of perfection, but I came to US at 18 basically alone and I knew that if I f——d up, I have no back up. This led me to be more proactive in how I conducted my life.
You can tell your friend that as a FRIEND, you are offering her a temporary aid to get her life together and that in 4 months you expect her to have employment and her own place. You can help her get baby stuff from garage sales and move her into her own place, but your reaponsibiliti is to you and your bf to maintain your own life. You worked hard to have your life the way it is, she can’t just crash this party.
Accidents happen, but everyone has to have a plan in place.
I never got pregnant by accident, she has a head on her shoulders to prevent that from happening.
It sounds harsh, but life is harsh.

Kick her out with a list of women’s hostels and job centre...

This is a great article from another board on codependency.... I don't know if you can relate to this or not ?

http://optimalwellbeing.blogspot.ca/2010/03/flight-to-intimacy-flight-from-intimacy.html?m=1