Best Friend?

I have a dear friend, she has been in my life for 13 awesome years. We have had our fair share of ups and downs. My friend who we shall call Jenny (to not keep identity a secret of course) has a husband in her life who she shares a home and two wonderful boys with. I have always have supported Jenny's marriage, even though her husband can put doubts in my mind whether he is suitable for her due to his behavior. But here here recently he has gone above and beyond disrespect and betray my dear sweet Jenny. I have expressed to my friend that I can no longer support her in the decision to continue to allow him to completely belittle her. Therefore there has been a rift created between her and I. I feel soterriblle for not being a support to my friend in this, of all trying times.

Am I being selfish? Or should I stick to my guns?