You know the advice I've received from my DB coach also conflicted with some of the advice given here. It's hard not to want to put it into action right away without any forethought but do give it some time to sink in. It helps because 1.)you're in a highly emotional state so anything you do will probably be emotion based. So, it would be hard to think like a DBer when you're emotionally invested. Not that it's bad to be emotionally invested but... B.) you're hurting and are wanting to reach out to her and 3.)refer back to number 1.
This whole going dark thing has been pretty confusing. There can still be a happy medium--I believe. I suppose you can still remain dark about your feelings for her while maintaining a friendly co-parenting relationship. Easier said than done I'm sure. I forget if there is OM. The fact that she's initiating even though it's not about the two of you shows she still has good will in her heart. You may not be able to win her back to reconciliation but she can learn to respect you as a father. So doing things with her and the kids will be an opportunity for you to showcase your changes. This could be your doorway.
How to get your mind of things? Um...stop thinking about it or really think on it. If it's painful and you're beating yourself up then stop the thoughts. Don't ask why or say but...if...but...just hit the brakes! If you're still stuck then you may have to just feel through it until in passes. I find that prayer and remembering who the true enemy is enough to get me focused again.
I heard a really good sermon this morning at a church I've been visiting during my stay here. The pastor said that once you've been welcomed into the flock (saved) then you've been enlisted in God's army. He then goes on to say that we are engaged in a spiritual warfare and it's not against each other but between our flesh and spirit...against the true enemy. And it's constant.
I read in one of my books that the enemy uses our emotions to get to our free will. He never makes us do anything. He deceives us and whispers lies in our ears that push us to our breaking point that makes us do the bad things. All of your negative thoughts are fed to you by the enemy and if you sit there and give it a minute of your day you will get sucked in. So stop having secret conversations in your head. Instead pray about it or talk it out with someone. Do you have a support group?
This could be your doorway. 
