This quote certainly opens a can of worms, doesn't it?
How often does this happen? You are struggling to maintain the status quo, to keep everything and everybody happy, to keep the situation from exploding in your face; and what is she/he doing? Why are you fighting so hard to "keep it together?"
It's fear, it's just too scary to even consider walking away from this relationship. There are a plethora of excuses why not to move on, but the reality is: it is just fear of the unknown, being alone, not being able to support yourself, and the usual "what will people think"? On the other hand, you may think that you love him/her, or you feel you can help them or fix them or you hope they need you.
All of these are just excuses, they may seem like valid reasons at this moment but this is not about them, it's not about the children, it is about YOU. You are staying because of your fears, not for any other reason.
If you really valued yourself, you would not spend one minute with someone that did not. So if you are in a relationship where you are putting in the time and effort to repair the damages done, and the other person in the relationship is not totally invested in that same mission, you are flogging a dead horse.
I understand that decisions like this are not easy to make. I also understand that you have history and "time served" to consider, but your health and happiness certainly deserve a fighting chance to survive. This person may not be the blessing you envisioned, but merely a lesson. When you understand what they are here to teach you, it will change your life; but for now, you will continue to do what you do, until you don't. In the meanwhile, work on you - trusting you, loving you, and embracing the wonderful spirit within .
"This above all, to thine own self be true" William Shakespeare