You know O my XW does the same thing. She has been dating her BF for probably a year now, posts nothing on social media about him, has never brought him to any of our kids events, has never introduced him to me but she has taken him with her to some functions with our kids and close family friends.
She also reaches out to me from time to time for weird reasons, sends me random pictures of the girls, asks me off the wall questions that she could figure out herself, etc.
Maybe they are temp checks, maybe she still has feelings for me buried down deep inside or maybe she just does it out of habit since we were together for 17. I don't know, I just keep moving forward.
I also am having the same problems with dating, opening up, being vulnerable. I think part of the issue is that I was hardwired to 1 woman for 17 years and it is difficult to re-wire my brain (or it at least it is for me). Everything about the current woman I am dating is different than my xw so that has been a struggle. I am just trying to be patient with myself and I like what AS said about trying to open yourself up a little bit at a time to help get comfortable.
Post D life is fun at times but it is not always easy. Hang in there!