First off, let me just say that something like this never comes at a good time. Sucks that it had to happen...knowing you as I do (which is to say, only from what you've posted here), I'm sure you're going through every emotion known to man at this point. But, as bad as the sitch is, you must not let it affect you're goals and progress to this point. In fact, this may be the best time to show that you are supportive. This will be a difficult time for her. No doubt she will be feeling a LOT of guilt about that, which will only increase the level of guilt she feels in general. The most important thing for you is to be as supportive as you can right now.
I'm sure you recognize that its not the end of the world because this happened. Please, stay strong for her, yourself and your children. You can do this, I know it.
"Achieve success, but without vanity; Achieve success, but without aggression; Achieve success, but without gain; Achieve success, but without force." Lao Tzu