(((((Tree)))))
I do think it will be all OK when you tell him, and I know you will tell him because it's eating you up inside.
I think you have a clear idea of what type of boundary crossing or violation will result in termination - this is not it.
So you know, I did download the pics from my exT wife's FB page (only ones with him, none of the kids). Put some on my phone, because I miss him SO much and want to see his smile. Just a way of saying, what you did is normal, how you feel is normal, and it could be worse, like mine?

@WePow, I tried to make a Mii of my exT; my 8 yr old kept asking who it was and then he deleted it.