Seems to me he's distracting himself with these chat things. And if he's waving it in your face that's purely to make you feel jealous wouldn't you think?
It's hard to hurt someone that you love/loved, and to have your hopes and dreams come to an end. It's a very sad thing and it's perfectly normal to be upset and emotional. In some ways it's worse than a death because the wound doesn't heal and there's always the 'what ifs' and maybes, whereas death is completely final.
Keeping things inside and pretending everything is ok might be his way to deal with it, but you deal with it differently and that's ok. Find people you trust that you can talk to in confidence, even if it's just here talking about it helps a lot.
I find that the people in my life that i have truely loved i still have feelings for even years later. But that doesn't mean i can live with them and i know my life is better off without them. It's also better for the children in the long run.
The one week for every month things is a rough rule of thumb but it does seem to have some bearing. One day you'll wake up and realise that you've moved on, but don't count the days, it will just happen.
A good exercise can be to write a list of all the things you like about your other half, and then also a list of everything you hate and can't live with. You'll probably find that the hate list outweighs the love list. And there probably won't be much on the love's list that you couldn't get with someone else.
Stay strong for your children and for yourself. You will get through this. But keeping it inside can drive you insane. DOn't be afraid of your tears or emotions, accept them as part of the healing process.
Good luck
Gilly