My friend said she doesn't wanna live anymore she is having the worst family problems ever please help!!!!?

This has been going on for awhile she is just 15 and has the worst life ever her mom drinks alot and her mom's bf drinks and does coc but the main points of her stress come when he fights with her bf because they have this huge fights and her mom tries to cut her wrist and commit suicide alot of times her mom is not there for her like she should be its all ust so messed up soo today her mom and bf had an argument and after it she locked her self in the restroom and started cutting her self my friend and her brother were trying to open the door but it was looked but when she did open it her littles brother walked in and saw everthing this happens alot and she doesnt know what to do she said she hopes she dies I just need some good advice to make her feel better!!!!!!!