I personally would not acknowledge the anniversary while he is involved with OW. But that's just me...
You know you and your H the best...do what feels right to you. Someone said to wait until the end of the day before you send the text to see if he contacts you first. I think that's a good idea. If he wishes you happy anniversary reply likewise.
(((hugs)))
M53 H54 D17 M33Y T38Y Bomb OW 09/09 OUT 10/09 BACK 11/09 OUT 01/10 WANTS TO R 04/10 BACK with OW 05/10 Wants to Reconcile 05/11 I said NO