I don't think a Christmas card is the worst thing you could do, but you dont' sound very detached, so I expect you can't do it without expectations. Therefore, don't.
I actually was a forensic accountant before kids (though I never worked on divorce cases; I did corporate work) and if you think your H is hiding things then I definitely recommend it.
BTW, if you think your H is hiding assets, why on earth would you send him a Christmas card????
Hugs, lady. This is a tough time of year.
Me42, H40 D12, S8, S7 A revealed: 7/13 Sep 4/14; Agreed to D 1/15