I don't know how good a friends the 2 guys are but have factored in the betrayal element within that relationship.
This could be a bump in a marriage that ends up having a great out come. His excitement at the thought of you being with another man could the tip of an adventure for you both. However not wanting to know and being excited seems opposite. But maybe he's been thinking/ wanting to open up for yrs this will be a great outcome for you both.
If he does struggle with the news perhaps some counseling to allow him a person to talk to without risking the whole town.
Invite him here as well
Good luck D