How as a Christian can you be happy for someone?

Mary
Ever since my so called godsis got pregnant she's younger then me and we been becoming more and more distant I'm not in favor because she is in college like me and no money . I can't be happy for her and or fake it what do I do her boyfriend is a bum a do nothing. She acts on and off towards me one minute she will speak when alone but other times she will not when other people are around. any thoughts ????