Send messages to ex-girlfriends. She is married, so am I. What do you think she is doing?

That depends on what message you sent! If it's just a greeting between friends, it's nothing. Although you used to be lovers, you are married and should keep your distance. After all, you all have families. It's good that she treats you as a friend. Don't think too much. If she is living well now, it is estimated that she won't care too much if you send her a message. If she is having a bad life now, she will care as a friend.