I am sorry your friend spoke like that to you.

Just a few things. First, she is lucky to have you as a 'true' friend.

Second, I advise you to step away now. The ball is in her court. You did the best you could, you've been a shoulder to cry on, you've been a true friend to her... which some people seem to take for granted. I'm not saying she is, but seeing she is willing to close her eyes re her husband's behaviour and spoke thus to you, this shows that she is not ready to listen and/or change yet. Thus, she will always 'choose' him rather than listen to her friend. This might or might not change, but it is best if you take your distance now as SHE could hurt you more in the long run.

I've been in a similar situation and it hurts when your supposed 'friend' behaves thus. I feel for you...