Should I just ignore her or what?

So the guy Im dating has a sister..and Im going to honest..this is the first guy Iv dated whos had one. I always thought it would be cool to date someone with a sister..cause My sister and I are not close so I thought maybe the guys sister and I could..Not looking for a replacement just someone who likes to do the same things as me...more as a friend. Anyways my boyfriend and I started dating back in May of 08..and at first I was excited and wanted to meet her..she wasnt ready. Which I was fine with because why meet someone if it just might end up in a break up right? So Dec of 08 she finally meets me. It was cool..I thought she was nice,pretty and seemed like someone I could go shopping with or just out to lunch and hang out. For Christmas she got both my boyfriend and I tickets to Universal's Islands of Adventure as well as she and her boyfriend had some tickets. So In Jan we all went..it was a fun day we all hung out and spend the day together..She talked to me and we kind got to know each other...well the best you can while waiting in lines.

So a few days later for some reason I got this itch that she didnt like me. I dont know why it just felt that way..and then I read some emails and found she was basically bashing me..so I guess my hunch was right. Well in Aug 09 her boyfriend and her had broken up and now shes living with him.

**Background story** See they are all from PA and my boyfriend recently moved down here to carry out his parents dream of moving here..So he bought a house and now they are both living in it until his parents come down in a couple of week..after that they will take over so my BF can move out**

Well come to find out shes pregnant..Im a mother to a boy and thought it was so cool that someone I knew was pregnant cause I love babies and just thought it would be neat to have someone close so I could be around the baby as well as her. Well I guess she doesnt want it..but she doesnt believe in a abortion(which is good) but doesnt want to give it up either..I was so upset at this. But anyways..the thing I dont agree with is she smokes (shes due in Feb). and isnt working..doesnt plan on it either. Now you would think oh this girl is what maybe 18-25? No this is a grown women..30. It just makes me so mad that she can be doing this to her child..anyways So knowing she really doesnt have anyone like friend to go through this with I offered to be along with her..if she needed someone to talk to, go to appointment with..a friend cause I know how scary it can be I have even looked for good deals on baby things for her. Well after this she started being a complete b---- to me. I didnt understand why because all I was nice to her. So now its to the point where I dont even want to be around her AT ALL. I mean iv tried the killing her with kindness..doesnt work at all. I have been completely ignored and i mean not even acknowledged..and it is kinda hurtful. So now I told my boyfriend until his parents come down I dont want to be over there..So I guess should I just stick it up and go over there and just ignore her or should I just stick to my plan about not going over there until he either moves out or their parents come down? And the thing that makes me hurt and upset is I might become family one day and I just dont understand cause then shes gonna have to put up with me..so she should get used to me being around right?