If you have known this person for almost 12 years, you were attracted to her many qualities and certainly knew her issues. Your post was mainly in defense of those things you do right (maintaining good health, mature attitude, emotions in balance etc.) and she does wrong. Please note I said mainly. You point to some good aspects of her personality, but more towards those not so great.

I think one way you might approach this is to see what you have been getting out of this situation. Have you been unwittingly thwarting your partner's growth because it keeps you in control?

Habits such as smoking are a sign that someone is quite anxious and maybe depressed. It is a coping mechanism, albeit an unhealthy one. Your situation sounds eerily similar to my own history right down to the one child because the child is a handful thing. If you two don't grow together you will probably grow tired of the situation, and because you are the one who is more professionally secure, you will have the option to check out of this marriage and start a new life with someone "more mature."

Or....you could work hard to see that you have had a hand in how all this has developed. I think that is where a good marriage counselor could help, especially before it is too late. I would simply like to leave you with one thought to consider...that you are getting something out of this situation as painful as it is. There is a power play, and she is stronger than she appears, I might conjecture. Because playing the "child" or dependent as the covert role is a strong defense. But there is also a co-dependency.

Without intervention and hard work it will end badly. However, the potential for growth is tremendous.

Your partner should be encouraged to pursue professional and lucrative work, and not be allowed to live and work far below her potential, as she may need the ability to generate income in the future. The greatest disservice to her is to allow her to not realize her dreams, personally and professionally, as she will simply fade into a shadow of her former self. Her poor self-care is an indication that she is stressed. It's not who she is, it is what she is doing to display her unhappiness. I firmly believe that attending to her needs in all areas will improve her standard of self-care. This comes from my own experience.