Hallelujah! Holy Shit! Where's the tylenol?
Make this date special for other reasons from this point forward. My wedding anniversary was the same date that the X and I started dating 6 years prior, so it had all sorts of nuanced meaning. I went to Las Vegas with SI friends on my first anniversary post D, and it was wonderful. I have that memory now.
If you have the means, make it the date you take your kids on that fabulous vacation. If you don't have that kind of funding, do something else special, even if it's just 'dinner out at IHOP' night or 'dessert for dinner' night. If your kids are old enough to question the date, make it 'the night I started planning you' night rather than focusing on the wedding aspect.
Me: FBS (no longer betrayed nor a spouse)-62
D-day: 2007 (two years before finding SI)
S: 6/2010; D: 3/2011