How do you tell your friend that shes messing up her life?

So my friend is 17, and shes been making one bad decision after the other. First she wants to waste all her time and energy on her bf (or ex bf now i guess) who is 25 and seriously does not care about the girl at all, he just lies to her, cheats on her, and blows her off and he has a history of hitting women. When she starts realizing that he dosent respect her, her idea of getting over it is finding a 28 year old sugar daddy who is a bit of a creep and is a bit on the controlling side. When she becomes even unhappier after this she goes and runs back to the 25 year old and trys to make it work with him because she says she loves him and cant live without him. Now her parents are on the verge of kicking her out and her solution to this is that if they do she is going to move in with the 25 year old. Ive sat down and told her my concerns about all this, and that she is only hurting herself and her future by making these decisions, but it seems that just as it starts to sink in it goes right out and she just keeps on with the bad desicion making. I cringe when i even try and think what her future a few years down the road is going to be like. I care about her well being as a friend but i just dont know what to do