<human>: Can you condense the text into a few key points?

Long complicated story - wife of 9 years, together for 15 in a happy fulfilling relationship. She has a long complicated history of mental illness and depression. For the most part she has been stable for our entire relationship, though she has bouts and has been in therapy. Over the last month or so she started to become cold, hiding things from me, and emotionless. 

We were trying to have children for most of this year and found out a little over a month ago that we couldn't, and it was because of me. During this time I have been travelling for work more than I have been home, and she has as well. We started to argue because I didn't understand why she was acting this way, and I found that she had started smoking again (we quit over 7 years ago). A couple of days ago, she told me that she wanted to leave. 

She says that she hates herself and has codependency issues (stemming from her childhood). She says she hasn't been happy for the last 5 years and although some of our best times and memories are in this span of time, she hasn't been dealing with day to day. She says she spends all of her time and energy into making sure I am happy at the expense of herself. She doesn't feel that she can be happy or figure out her issues unless she goes away.

I'm shattered. I want to be supportive and help her. She can't tell me if she will ever come back because she doesn't want to make promises to me, because that would be counterproductive and she would be trying to make me happy when she doesn't know what is going to happen. I've convinced her to stay while she starts counseling and I will give her all the space she needs. She agreed, but still seems adamant that separation is inevitable. She swears she loves me and says that we can never have the marriage I deserve unless she learns to love herself first. While I am trying to be accepting that maybe she is right, I will never be able to really understand what she is going through. All I see is her throwing away what seemed like a happy marriage instead of trying to work things out. I don't know what to do.
<bot>: Wife with depression needs to leave to find happiness, and I want her to be happy but want to save our marriage.