Ugh, I hate that you had a bad weekend too! Kudos for handling yourself so well. I know it's difficult to tell your oldest he has to stay with his dad, especially considering all he told you about OW. But know that you're doing the right thing for him, you and youngest son.
Keep up the good work, there is light at the end of the tunnel.
If you love somebody, set them free. http://tinyurl.com/2empx2g