My best friend is screwing her life..how do i help her?

she is 32 and had undergone an abortion whn she was 26. that guy is married now and wants to get back with her. meanwhile, she is having a casual relationship with another guy ( no commitment only meeting for i guess). theres another guy who likes her and wants to marry her..but she is losing her interest in her as he isnt that great as the guy whom she is with now ( no commmitment one). she says she really likes how they make love and dont wanna lose this guy..but i feel this is ruining her life..she is stuck in a relation that has no future and is losing on a guy who wants to marry her. i knw her since she was 10 years old, we are school friends..i talk to her daily and try to change her mind..but she just doesnt listen..what shd i do?