My stepdaughter is 15 and pregnant....

So, my stepdaughter lives 3 hours away with her mom. Around January, we noticed that my stepdaughter was "talking" to this kid on facebook. I looked up on him and figured out that he was a drug using pos that had been placed in an alternative school because he was suspended so many times from traditional school. My husband and I tried to talk with our daughter about this because we were very worried. She stopped talking to us and her mother, my husband's ex, refused to even communicate with us about our concerns. We have always had concerns about our stepdaughter, mainly because my husband and his ex got pregnant young, but the ex didn't want anything to change for her daughter. She didn't value school, took the kids around all types of no good people, works the system to get additional food stamps illegally, etc. And now, our 15 year old is pregnant and she wasn't even the one to tell us. I am also pregnant and my husband and I have a 3 and a half year old. We really don't know what to say or do, mainly since we have been closed out by the daughter and ex because we believe in rules and don't agree with this type of thing. I have been praying about how to handle this but am just so confused and saddened by the situation. I certainly don't want my 3 yo to think this is ok and to be confused by the fact that her sister has a baby. I also don't want my stepdaughter to feel like I am condoning this behavior either if she does decide to try and reconnect again. I really would like to see her finish school if possible and get some kind of certificate through the community college, but I don't foresee this happening. Her mom doesn't work and like I said, plays the system. We just wanted better for our daughter..... :(