Brigid: I am glad for you in being "the better person" (IMO) in extending yourself, at least in a birthday card, to your ex.
I attempted this at one point.
When my second marriage was not doing so well, in no small part to my wanting to be a better person (he did not, he wanted to drink and run away from his issues) I decided I would be the one to put out the olive branch, as it were, to my first husband and his wife. I did this mainly because I was sick of watching how uncomfortable my children were when it came to my relationship with their dad and I was sick of having so much tension in my life.
So it started with a chair that was in my house in sight from the front door. My first ex noticed it once when dropping off the children. It was an unusual wooden chair, that his uncle had given him. I said, "you should have this chair, I don't know why you didn't take it 6-7 years ago, but you should take it now".
He got all embarrassed and said "no, I'm not taking furniture out of your house". So the next day, I took it over to his house. He and his wife were flabbergasted. I simply said, "this is your's, you should have it".
I thought I had started a good thing. A healing as it were. Tensions eased after that, or so I thought UNTIL: I had the audacity to want to get on with my life and move away from here. Although he was in another country at the time and for much of each year, all hell broke loose and many court hours and an unGodly amount of attorney's fees later, I am still here.
So you see....if I had stuck with a chair, a birthday card, something benign, that didn't go against his permission, his control, his wants, everything would still be hunky dory. This kindness on my part, by the way, was brought up by his attorney in court, to say what a bitch I was, and how could I possibly "DO THIS" (what, want my own life?) to a man I was "friends" with (who did and does whatever he wants, and now can, with the courts permission...but I digress).
I'm not trying to be a wet blanket. I don't regret the chair.....I just realize that with an N, kindness doesn't matter, and if it can be, it will be used against you, if they so deem.