I'm glad you will work through the drama and you are stepping back some. Could not go on the fetlife thread to defend -- just deal with him direct. You have enough going on without more people in it.
You could have told him "Hey, since we have new boundaries I wanted to let you know to remember to check your gmail/googleplus. I rarely use it but I wanted you to know I turned my link to you off on my end. I also want you to be aware that by clicking on you, people can link to your kids mom stuff, and there see pix of the kids. So if that bothers you, you could review your Gmail/Google settings not just to me but others."
Then he can choose to unlink the mom and/or talk to her about the kids online presence.
Again, if he is this nervy about this digital information, he could not link to you. Totally makes it a non-issue. Do HIS side of the job so he can feel about about his digital prescence/connections online.
Alternately you could have disconnected from him in your gmail/google things and keep your end of the deal. Told him you disconnect there to honor your agreements.
And in noticing that he has loose things flapping out there from connecting to other people? Could NOT tell him that bit at this time. Could remind him to check his gmail/google at some other time later down when the recent hooha isn't so fresh so he doesn't retrigger. And at THAT time, let him choose to deal with it or not. Wouldn't kill anyone to hold off on the reminder for a few weeks.
He seems to have a problem owning that what he connects to is HIS BEHAVIOR. And he can control his behavior.
But in your behavior -- you seem to be very impulsive. I think stepping back and learning to not plunge ahead with whatever it is RIGHT NOW could be a good thing.
If he's not helping (you and him) to meet new agreements and you are not helping (you and him) to meet new agreements in this transitional time while (you and him) are reviewing your individual digital things and personal behaviors -- why make these agreements?
Hang in there.