Since this is her parents, you can't and shouldn't do anything!  All you can do is be supportive of your girlfriend.  You cannot alter or change what is going on between her and her family....if you try you will just be controlling the situation.

Listen this is all about her coming out to her family.  Sounds as if it is a difficult coming out and she is going to have to work through that in her own way.  And to be quite honest, some days she may want to tell them to eff off and the very next day she may want to cry with her mum and say she is sorry.  Tis the nature of family.  So you need to be supportive and understanding and allow her to take the lead as to how invovled you are in this.  But honestly, I know that you are affected by all of this and I know it hurts you to see her get treated poorly.....but in reality since this is between her and her family you can't say crap to her mum.  It isn't any of your business, it's hers.

Instead focus your energy on listening and being supportive of your girlfriend during this time....it has to be hard on her.

Thank you both for your replies!

I guess you're right, I should just step back - it's not right to intervene afterall. I'm just struggling to make it all ok! :(

I know she needs my support, and she knows I'm always here for her.. I'm doing my best to support her but somehow it doesn't feel like I'm doing enough. Maybe it's just because I desperately want everything to be ok and not being able to make it ok feels like a failure to me.. I certainly don't want to seem controlling so I'm ruling out the option of talking to her parents..

Oh I certainly don't want her to think this is about me! I know she had a great relationship with her mum, and it would be terrible if they lost that.. We talked a bit about it today and I made sure I told her a couple of times that I'm right here, whatever she needs and whatever she decides to do. The problem is that her parents just won't listen. I suggested she write an email or a letter, if she feels she'll express herself better that way. Anyways, I agree that I shouldn't inervene and make her feel she was a 'wall to lean on'. I just have to deal with the fact that I can't fix it all!

:)

[ I carry your heart.. I carry it in my heart.. ]

I think the best thing you can do is just show your support to your girlfriend. Communicate and let her know you're there for her no matter what. This is something she has to deal with, but that doesn't mean you have to let her jump these emotional hurdles alone. 

Another thing you could do is brainstorm some ways that she might be able to help her mom recognize your relationship. Each person is different, and so confronting homophobia is always a unique process. Think about how they operate and whether her mom prefers more casual interaction or needs to feel respected in a more formal sense. Could her mom respond well to discussing queer issues in a hypothetical arena? what about watching ellen together? would a heart wrenchingly honest "listen, I really like this person and I'm sorry, but this is who I am and I really hope that with some time, I hope you can learn to respect that" be too forward or just what she needs to hear?

Good luck to both of you!