Im assuming you went to look at the pictures before realising you had been un-tagged, I dont use Facebook in much depth so im not too sure how it works, but I would say if you were looking at those pictures maybe its a sign that you need to move on and do the same. ie. Erase him from memory.
I tend to do this, If i split from a guy I try to do it in the nicest possible way but gradually remove myself from the equation, I dont see it pleasant to have my new bf round for dinner whilst texting/inviting the ex also. "Hey X meet Y im sure you will have LOTS to talk about" haha... just wouldnt work.
If hes an ex, its for a reason, move on and be happy, Im sure he has. Good luck sweetie