Need a woman's perspective... She said the wrong name during sex

So I'll try to give you some background without making this too lengthy, but I want to give you a full understanding...

I've been seeing this woman for nearly four months, she works at the office where I work, she's just gotten done with a divorce from a 10 year marriage right before we started hanging out as friends, and then it started being more. We said from the beginning that we'd keep it casual, because she didn't want to jump into anything serious. But we've really been in sync in so many ways, we make the same jokes, and when we do we find the other was already thinking about the same thing, we have the same sense of humor, like the same things, and the sex has been fantastic for both of us, we find ways to steal kisses here and there, or to secretly get together after work, or over lunch hours, spending the weekend together here and there. Feelings started to develop quickly, and it's really been great, she does special things for me, I do the same things for her, like she mentioned once in passing in an early conversation that she loved horses and horseback riding... So a couple weeks ago I surprised her by taking her horseback riding, she loved it, and she was really touched that I had paid attention, and remembered what she said...

Now that being said, we've been keeping it quiet, nobody at work knows about us, none of my good friends know, nor hers... Cause most of them are also coworkers. She also has two sons, and wants to give them time to get used to the divorce before introducing a new guy to the picture, which totally makes sense.

So on Friday, a group of us go out, she invited a couple of her guy friends, I invited some of mine, we had a great time, and later that night, she and I are having wild passionate sex, and she starts moaning, we'd both been drinking a fair amount, and then at one point, I realized... The name she's moaning is not mine. It's her friend's name Stephen. This guy has been a good friend of hers for a couple years, and he was with us when we were out that night, he's had a crush on her for a long time, and they are always hanging out with her, and her sons, and has been a good friend, but he's totally in love with her, she knows it, but isn't interested in him, he's super clingy and needy and she gets pretty annoyed about how he's constantly around.

So the next morning we talked, and I told her what happened the night before, she was mortified and felt horrible about it, and apologized profusely. We were talking and she was assuring me that she wasn't thinking about him or wishing that she was with him, but I said that the fact that she had done it makes me wonder if there's some unresolved feelings with her and this guy. And it was awkward how we left it, she was asking if I needed space, and I told her that I didn't want to lose what we had over an accident like that, but it was still very uncomfortable, and we haven't talked since.

I really don't want to lose what we had, it's been great. But I'm hurt, and feeling very uncertain about things. I know she cares for me, and I think we were falling in love, but have both been a little too guarded to say that because of how quickly things have been happening. What I really want, is a sign from her, that she's sorry, that this relationship means as much to her as it does to me, and that she's willing to fight for it and work to save it. And of course I can't really expect her to be able to read my mind about what I want, but at the same time, if I tell her what I want, will it be as genuine?

Thoughts?

I wouldn't feel comfortable with her having a super clingy male friend after that, especially if he's in love with her. She either has some fantasies about that guy or a private affair with him.

In vino veritas.