Advice Needed: My Role as a Friend and as a Feminist

I have a couple of dear friends who’ve depended on me a lot over the last few years. Sarah and Daniel (not their real names) started dating in late 2006, and by the spring of 2007 she was pregnant. They depended on me a lot during this time, because they felt like they didn’t have anyone else they could trust. They were probably right; we were living at a university populated almost entirely by uptight, overachieving white kids, and Sarah and Daniel didn’t fit the mold. Sarah was impulsive, irresponsible, and unreliable; Daniel was Mexican, not college-educated, and unemployed. They were targets. By April of that year, they moved to California to be closer to Daniel’s family, since Sarah’s (conservative and racist) family had made it clear that they would have nothing to do with the baby until Daniel was out of her life.
Their daughter Maria (also not her real name) was born there and they all lived together until this past spring. I’d been out to visit them once, and from what I could tell they seemed very happy even though Sarah’s parents stood firm in their decision not to see or speak to any of them. Daniel’s family, however, was loving and supportive. Daniel had a job, the three of them lived in a nice apartment together, and their relationship seemed happy. However, this past March, Daniel came home from work one day to find Sarah, Maria, and all their belongings were gone. He called me immediately and we spent days trying to call her, and to call everyone who might know where she was. Finally, after days of unreturned phone calls, her brother admitted that she had come home to live with her parents. The last six months or so have been a mess of heartbreak, legal action, and custody problems. The case hasn’t gone to court yet because California and Illinois are still fighting it out over where the case should be tried.

Over the last few months, I’ve tried to stay out of it as much as I can. I care about both of them so much that I’m finding it very difficult to take a “side.” When they call me I’m there for them, of course, but I’ve been trying to avoid initiating contact. I’m very worried about getting dragged into the legal proceedings because I am literally the only person who knows both of them well; I’m literally the only person who could possibly give an unbiased statement regarding the matter. And I’m terrified of being wrong. Her side of the story is that Daniel was “emotionally and physically abusive” (I don’t have any other details regarding that accusation), and so she had to leave. She has gotten a two year restraining order against him.
I have a lot more details about his side of the story because I was his main confidante in the first month or two after she left. He said they’d been fighting a lot over Maria’s care. Sarah was a stay-at-home mom, and Daniel had been working 10 hours a day. He would come home from work and find that Maria hadn’t been fed or changed all day, and whenever he asked Sarah why, she would say she was just too tired and ask Daniel to do it for her. He would do it, of course, but apparently not without a great deal of nagging. He believed this nagging to be what had driven her away.
[trigger warning for domestic violence] He did admit to me that he had been physically violent once. When they first moved to California, she left a file of saved IM conversations open on the computer while she was in the shower. The conversations were with the man she had been regularly flying to Washington DC to cheat on Daniel with in the month or so after she first got pregnant. Sarah had ostensibly chosen to break it off with the other man and be with Daniel, but in these saved conversations she had told the other man that she loved him, she had sent naked pictures of herself to him, and she had told him that she wished she were carrying his baby instead of Daniel’s. A huge fight ensued wherein Daniel slapped Sarah across the face twice. According to him, this was the only time he had ever been physically violent against her, despite the fact that she hit him regularly. Goodness knows, I’m not justifying what he did. It was entirely wrong and he knows it. However, it was not (according to him, at least) a pattern.
I am unsure who to believe. My gut instinct is actually to believe Daniel. I know both of them very well, and his story is much more in line with their characters (as I perceive them) than hers is. This same gut instinct tells me that Maria would be much better off with him than with her. I know that Sarah likes to just disappear across the country without telling anyone where she’s going periodically. (This most recent time was the 4th time since I’ve known her). I believe that she was physically violent much more frequently than he was. I know she has no problem lying (in fact, in one of our very first conversations, years ago, she told me how much she enjoys lying–she actually considers it a hobby to see how much she can get away with) and I don’t doubt that she would be willing to lie in order to get that restraining order, nor would she hesitate to lie in a custody hearing. I believe his story that she would go whole days without feeding Maria or changing her diaper. In short, I believe Daniel’s whole story.
However, my feminism compels me to not take the situation at face value. What if she’s telling the truth? What if his words were not just, as he said, nagging her about changing Maria’s diaper but actually were emotional abuse? What if he was regularly abusive and lied to me about it? What if she only stayed so long because she was afraid of him? I also know that if the custody hearing happens in her hometown, Daniel won’t stand a chance. Racism alone will decide the case. California is the only place where he’ll even have the possibility of a fair hearing. On the one hand I desperately want to avoid getting dragged any farther into their personal life than I already have been–on the other hand, my concern for Maria’s safety is very strong. My inability to be certain which parent would be “safer” for her, however, is very disturbing to me.
What is my role both as a feminist and as a friend in this situation?