Alcholic sister???

My little sister is 25 years old. She is a bartender at two different bars. Her life is spiraling downward and fast. She is drinking to the point of blacking out about 2 to 4 times a week. This has been going on for at least 4 years. She was always very responisble finacially and with her body. Now she spends 100's of dollars drinking every week, spends $200 on 1 pair of jeans and she cant make her house payment. Worst of all she is trying to get pregnate with this guy she in infatuated with who drinks just as much if not more then her. She saids she thinks it will force her to settle down. No one can talk to her about anything, she freaks out if anyone even asks her not to swear around the kids (my kids and little cousins). I dont know what to do. I love her but I cant talk to her because she flips out, this christmas she said she dosent even want to be around the family anymore. What should we do to help her???