I'm so sorry that you are here. I too have two S's 19 & 15 and we were all blind sided by this. My H has OW and he keeps asking me to get a D since I can get one quickly because of the A.
To file or not? That's a tough one. I personnally am standing for my M and refuse to make this easy on my H. If he wants out than H will have to file.
Pack his stuff for him? NO!! He wants out he has to pack and carry his own stuff out of your home.
Keep being sweet. Have only kind words to say. Don't raise your voice. Be the better person. Pray the whole time. Your S's need you now more than ever.
If you haven't read Divorce Remedy yet. Buy it or check it out from your local library.
Work on yourself. Make yourself happy. I know that it seems impossible to right now.