OP, I'm so sorry. And the cheek of it to now act like he's the victim and need you to comfort him. He should have the dignity to leave you alone! He won't though, he'll cling to you and explain, try to get you to keep going with the role he's assigned you (holiday and life organizer).
Everyone has given you good advice, I'd use that cold distanced feeling you have right now to give yourself some space from him, be calm, get another room and then get back to someone like a friend or your family. I would tell them all, another reason men often want you to shut up is so their image isn't damaged, but he's been having an affair for half your short marriage and that ship has sailed.
You do what is right for you- if that be he gets out of the hotel room and pays for another one, that's what happens. He has no right to your sympathy, or comfort or for you to reassure him (panic attack? let him call the OW for reassurance). Talk with someone you trust, or in fact anyone you feel like talking with, don't feel the need to keep his secret now, he's probably hoping you'll not tell anyone so he can get you back on side and then make up his mind, but that's not going to happen.
In years to come, you'll see this as a turning point for the better but right now, the sting and the betrayal is yet to completely hit- comfort and cushion yourself, not him. Do whatever you have to do to cope.