I completely understand your predicament. You want her to feel like you're on her side rather than blaming her for always falling back into the same old unhealthy habits.
Tell her that you love her and want to help her to free herself from the manipulations of her abusive ex. Tell her that your wish to understand her led you to reach out to me. Tell her that I explained that when a person is drawn to abusers it's because he/she is trying to work out a relationship with an abusive parent.
I recommend that she use my Personality Profile, which will pinpoint the exact wound she suffered as a child and guide her on how to begin to set limits and separate from an abuser. As she becomes more self-aware, she's going to discover that she returns to the abusive ex in the hopes that this time around she can succeed in being loved not abused.
That's what she hoped would happen with her abusive parent. And this explains why she keeps going back for more hoping that this time the outcome will be different. What's more, all abused children believe that it's their fault that they're being abused. As a consequence, they passively accept the abuse and reward the abuser by being always more 'good' or compliant.
The fantasy being that one day the abuser will wake up and see how good and obedient he/she is and reward them with love. Of course this pattern never works. Compliant behavior just encourages the abuser to continue the abuse.
I've given you a brief explanation of why it's so hard for her to break free of her ways. Giving up an abuser feels like giving up all hope of making it right with the parent who harmed her. She's going to need to feel all kinds of feelings, hurt, anger, disappointment, etc. in order to heal and let go.
My Personality Profile will guide her on how to do this.