Well done! That just shows you are already great at the GAL technique that you will read about in the book. That is great you are good with tools, I am absolutely dreadful at all of that and it has proved to be a bit of a problem at times!
There is always debate about birthday cards etc. I don't see any harm in a birthday card/ ecard. But keep it simple for example just 'Dear H, Happy Birthday, DestinyUnknown'. Know loving messages etc or I love you's. The WAS does not want to hear that stuff.
With the divorce conversation, everything is still raw at the moment with you and your h. The key is to get both of you to stop reacting. His divorce threat is a reaction. Therefore you need to start being calm, and most of the time don't disagree with them - however this doesn't mean that you should protect yourself practically and financially. It is called validation and often takes the threat out of a situation so they stop feeling the need to fight against you all the time. Work on you, being confident and looking your best - this is attractive to the WAS even if you don't feel like it.