Everyone I've told so far has been okay, and I'm certainly comfortable with backing up my decision to friends. I also would want to behave with integrity with anyone I was involved with, not just my wife, so yes, taking that person's needs and feelings into account is important, as is making sure everyone is treated in a way that values them. I expect I'll sort out where the lines are between discretion and secrecy for the specific people involved when the time comes.
It's all hypothetical right now, as I'm not seeing anyone other than my wife, and probably won't even remotely go there until the dust settles on our relationship change. I'm still grieving the loss of the relationship I'd hoped to have with her, and once that is done I trust that I'll know what to do then.