X Gf Trouble

Recently me and my x gf split up, due to her cheating on me. She was totally crazy about me and she went through a period of depression and guilt after, and has since begun dating another guy, telling me she went with him because it was 'difficult to turn down sum1' who offered her love, and because she 'always needed someone'. After a while of this she was texting me saying she loved me and wanted me back, until 2 weeks ago she found out she is pregnant with his baby(she doesnt believe in abortion). They are now engaged (because neither of them wants to bring a child up outside of marriage) and she is living with him, and when speaking to me all she could do is cry. They have been dating just over a month, I dont know what to tell her. They are also both only 18. I dont believe she would text me every day if she truly loved this guy, but I cant offer a home and i'm not the father.. And I don't want her back now anyway, so she hasnt got much choice but to try and make him and the family work (her parents are both dead). But I care about her and it seems to me she is feeling forced into doing all of this, and is going to end up either a single mother or stuck in an unloving relationship (which hurts both parents and the kids). She won't talk to me anymore because it makes her cry everytime - she wants me back but has now been forced to stay with this other guy. Should I advise her or do I have to just stand by and wait until she finds out the hard way? Or is it possible that she is lying to me in her texts to keep me as a backup (altho she has now broken off all contact), and maybe she really loves this guy and the marriage could work? Any opinions gratefully received.