I'm afraid I handled 'the talk' fairly badly. I told my H that since he was the one having the A, and wanting to leave his family, then it was up to him to tell them why. Fortunately (or not, depending on one's viewpoint), the kids already knew something was up. They are older than yours (the twins were 17, youngest daughter 11, and oldest married daughter was 25), so were quite aware of something boiling. My youngest got very upset, and she is still very wary, and clingy with her dad ... gets very antsy when we have a disagreement, and we have to reassure her that it is just a disagreement, not a fight. Anyway, my H pretty much told them that he still cared for me, but wasn't happy anymore, and that he felt it best that we got divorced, but he still loved them and that nothing was their fault. I just stood there in self-righteous silence (oh grief, the old me was such a b!tch, even though I had reason to be sometimes). Not sure if doing this made him realise what he was losing, and it finally leading him back to us. He, ultimately, never left the home, and it was about 6 months after 'the talk' that we decided to reconcile.
Good luck with it, WII ... it's a very difficult thing to have to do, but with the ages your children are at, just keep it really simple.
Me:57 H:52 M:28 Got another lawyer last year and filed. D35,S/D twins28,D22 EA4/04 End? Who knows? "Life is like a mirror. Smile at it and it smiles back at you." — Peace Pilgrim
