Hi Red, you won't need to ask if OW is near your kids as they will tell you. Also you ask about her, you are showing to H that you care. What you want him to realise is that you will be fine on your own without him. Yes she was your BF, but honestly who would cheat with their best friend's H.
Let your H files if he want but if it's not what you want don't do it.
Regarding the cousin's wedding, we are in February and it's in April. You still have time to decide what you want to do, again no rush here. It's up to you if you want to go. If you don't want and you'll know she will be there, decided what the best is for you.
It's hard as you have had a traumatic shock. Don't try to do everything at once, like you I couldn't eat, so went for last resort technic : chocolate :-)!