Sister advice?

The past year my sister has been having relationship troubles with her boyfriend. I was there for her through everything. She couldn't decide if she wanted to be with her ex boyfriend or her new boyfriend and kept getting back, breaking up etc. My family are pretty sick of her with all of her drama, despite us being there for her. 
I recently found out that I'm pregnant and I'm so excited. But she hadn't been there for me at all. I couldn't go to her nephews birthday party due to really bad morning sickness and she didn't even ask me if I was ok. I'm unemployed at the moment but still bothered to buy Christmas gifts for her and her 2 children, and I got a gift for my nephews birthday also. 
She didn't bother to wish me a merry Christmas. I'm really hurt that I spent so much time being there for her and she won't give me the time of day. I would understand if she was really hurting, but all she has done the past month is go on nights out with her friends. She cares more about creating the perfect "view" of her life on Facebook. 
I don't think that she even knows that she has been ignoring me. She can be so selfish and self centered at times that I think she hasn't even noticed that she has been ignoring me.  I think she might be having a mid life crisis. 
I'm so hurt that I'm not sure if I'm being unreasonable? I've never had a fight with her (she's 11 years older than me so we didn't grow up in the same house as kids) and I don't know how to approach my feelings with her? 
Sorry this is so long, I'm just feeling like I don't have very many friends since I've shared the news that I'm pregnant ?