I see two things coming into play here. I only have a second because im headed to bed and will make this later longer, but i read it and heres what I see:

-Marcie is the type of woman who has a traumatic past and is still locked in the "play the victim" mode. I am not a professional but she almost sounds borderline to me, I have borderline and the whole "I hate you dont leave me" or going from Hot to Cold like that can happen. I think that Marcie probably latches on to people because she desperately NEEDS that attention and caret to feel good about herself, to feel whole, and to feel like a woman.

-You seem like the type of man who desires "saving" the damsel in distress. Actually this happens in not just men but also in women. I dont know if its an actual personality disorder, just a quirk, an illness, or what. I have it to so I can relate. For me there is a great need to "fix" people or "change" them for the better. And that can get the best of a person.. You should only give help to the extent that you can healthily do so. That can be hard.. because its hard to detach from someone you care about, and I think you care about Marcie a great deal. The problem is if you continue when its actually detrimental(to either you, her, or the situation itself) its almost bound to have bad effects. She may not be ready, she may be too ill, she may be a drug addict, she may be simply too traumatized to take in the information you so desperately wish to give her. Heck maybe she just doesnt want to see it and is in denial.

We can't be everything to everyone. Thats the thing. Having a "savior" or martry complex(i think that they can be similar) can go too far. It can end up causing us harm because it takes so much out of us. I wouldnt go so far as to say you gravitate towards women with issues- but your first wife has some control issues, and Marcie has some issues.. perhaps you might look at what about that has attractedyou/if something in that has attracted you and why. For me, and this sounds oh so cliche.. i wonder could it have something to do with the fact that you had issues with your father. Perhaps in seeing how he was, you so greatly wished to be more of a man/a better man/ ect than he was or perhaps you are trying to fix people because you couldnt fix your father. I say this gently.. Im sorry if it comes across harsh. I think these are important things to look at in this situation. Could be just my thinking cap making things up but thats where I would start!

More later