Been keeping away for a while. Catching up on your sitch. Holy sh!t, same freaking thing! Same. Freaking. Thing. My W also dropped my last name from her Facebook profile two months ago. It's like a damn script they all follow! I didn't have the same reaction you did, because my W is having a full blown PA, so seeing her go without her last name on FB is a drop in the bucket to me.
I will concur with the others that you should keep your mouth shut. I know it's hard, really hard. You want to point things out to her, especially if the MLC has made her kind of dum dum at times. It's true, though - never let them see you sweat. Any challenge you offer looks like she's still got you on standby.
M: 49, W: 45 T: 22 M: 15 S14, S11, S9 BD: Jan '16 W files: Oct '16 D final: June '18