Supporting a friend in an emotionally abusive relationship

[Starfish2016]

Hi - this is the first time I've posted anything like this and I'm also a guy so please be gentle with me!

I have a dear friend who's in an emotionally abusive relationship. I've known her for a couple of years but I've been around her partner for far longer, and he has a history of short-term relationships, infidelity and narcissism. She's a very clever woman but hugely lacking in confidence and has quite low self-esteem, and he wooed her by saying all the right things and making her feel special. She was aware of his track record but fell head over heels very quickly. Unfortunately, he became verbally abusive and controlling early on, left her at least once and was generally volatile and unpredictable (mixed with periods where he was charming and calmer).

A few months ago my friend went through a very stressful period in her wider life. Her boyfriend walked away from her at one point, saying vile things in the process, and when she took him back he continued to be flaky at best in terms of support. I and others close to her rallied round to help her through this crisis - he wasn't there for her and his cruelty contributed to her near-breakdown. Then, after all that, he proposed to her, again saying all the right things, and she accepted because she loved him so dearly.

I've been hugely conflicted ever since - clearly my friend is in charge of her life and is the only person who can decide what's right for her. I can offer advice but can never tell her what to do. Equally, though, I'm so worried about her future with a volatile, abusive husband; she herself has acknowledged my concerns are valid and admits she also fears it'll be an emotional rollercoaster, but wants to give him the benefit of the doubt.

The saga has taken a huge toll on my emotional wellbeing and I've distanced myself slightly as a result. I've explained I'll always be there for her without judging her, but that she has to take some responsibility for her decisions. I hope I've done and said all of the right things, but if anyone has been in a similar situation, I'd appreciate some reassurance that I couldn't have said any more. All I've ever done is to try to be a good friend and an honest person, but I can't let her relationship drag me down too.