How difficult for you, and I so understand your hurt and pain. I hated England for awhile until OW moved away from there. And now she's in Canada, so I can't hate my own country, although I will never live in the city where she lives. So, I know of what you speak. England has gone off the hate list now.
Don't beat yourself up too much. Your S has to know something was happening when your W left and that must've been just as stressful as his first day of school. Still, your timing could've been better. You can't protect them completely until things have been resolved one way or another. It would be best for a reconciliation, but it may not go that way. Kids have weird thinking that when mommy and daddy split, and they are unaware of why, they tend to think it's their fault somehow. Now, he discovers that daddy doesn't like 'said country' and mommy does. Perhaps he's going to think this is why mommy left. Make sure he knows that it's not his fault, and make sure he believes it.
Your W left, is having an A, so what the heck did she expect was going to happen? Nothing in the M, except abuse, should turn a person to someone else. You try and fix it, then you leave and find a new person a time after.
As I said, don't beat yourself up too much. Accidentally, spill a lot of ketchup on the t-shirt. Well, I would. I tossed gifts that my H received from OW. Your home is the marital home, therefore, nothing pertaining to the OP should taint it, if possible (in my mind, anyway).
Sorry, not much advice, put a lot of empathy.
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