Upset

I just found out yesterday my sister is pregnant. She is with a guy who is lazy, doesn't clean the house and doesn't help her with the animals. She is 18 and mom and I know she isn't ready and she can't do it on her own but she can't seem to see how he isn't gonna be there. He plays game on his PS4 all night long and when she barley touches him goes ow and yells. I'm more frustrated that she is pregnant with this guy then her being pregnant. How can I help her and get over my anger with her lazy boyfriend? She also smokes cigarettes and last time she tried to quit failed and so doesn't her boyfriend. Along with weed. I'm more afraid her baby will be taken away because of the weed. Also mom seems to think that my dad who recently passed away would be okay with this when I know for a fact he would not be. I can't wait to leave and never look back.