You are doing more than fine, remember detachment is good but it has it's place and I see nothing wrong in what you have said to the puffer.
I do see a good part in all of this as well, you found out about the OW. Tha A will be much more fun for him in secrecy than it is now that he has been outed. I got a gut feeling the niceness is due to the fact that you found out about OW, now that you know for sure he is probably afraid you will move on so he is trying to pull you in a bit.
You don't have to thank this poolboy for putting up with you, to me it is an honor
