Hey T, here are some thoughts, but, I think that overall you did a great job.
She went off on you. So what. You didn't know she wasn't going to be there and S didn't tell you. Mentioning that all she had to do was call was good. She blasted you for not telling her where you were going?? So what. You don't have to check in all the time, but, I ran into trouble with this one because W calls to talk to the kids every night. One Sunday night, she couldn't get in touch with me because I was ignoring her calls and when she called the house, no one answered because they didn't hear the phone. So, her fear started running away and when I finally talked to her and told her that the kids were home with my Sister and that I was out with friends, she blew her stack. That said, I think it was a good thing overall. It lets her know that I'm not sitting home with no life while she is up in the mountains with friends and not telling me about where she is going or what she is doing. How did I know? I snoop. It's a bad habit.
The e-mail apologizing for her mood. I wouldn't do that. It may be an artifact from my past pattern of apologizing for everything. Perhaps an e-mail saying just that you didn't know that she wouldn't be there and that she sounds pretty stressed.
However, she called back and apologized which is good. I wouldn't have brought up how you felt ignored, but, instead just say that you didn't realize you were coming off badly in e-mail and that you would work on it. Offering the massage was OK. Reiterating that it was available any time was I think a little too much.
Overall T, I think that you did very well and it looks like your W is maybe not quite as gone as you first thought.