MGuy,
There is going to be a time in the near future that you crash (IMHO). You can not make her happy...I am not talking about "buy her flowers" happy....I am talking about deep down inside her core happy. This is something that she needs to work on herself. Whether it be a chemical imbalance or not (clinical depression vs. depression), it is all still depression.
No matter how much you want to try and love her out of this, you can not. What you can do, is stand by her and support her. You are doing this now, and I think you are doing it well. What she needs to do is talk to someone. We all get "trapped" in our life some times. Money, work, friends, family, children, relationships....these are all life variables with their own little rollercoasters. I have been there. TRUST ME, I have been there. I talked to someone.
She can go to her family doctor and request to speak to a therapist. Fraser Mental Health offers a variety of different options anywhere from support groups to one on one counselling...FOR FREE!
Mental Health Services - Mental Health and Substance Use - Fraser Health
Check out their website and call. If this is not an angle she would like to choose, then her family dr. can recommend a psychiatrist or a psychologist. This can be free as well. Other options are doing it privately....you can google neighbourhood therapist who specialize in depression and anxiety disorders...couples counselling...family counselling, etc.
Honestly, the first step is the hardest but it is worth it. She WILL get better. We ALL get better. There is nothing to be ashamed of. Once you or her surrender yourselves to the help of a professional, it will take a lot of weight of both of your shoulders.
I really hope you call someone