Good job holding the line on equal Xmas custody! I enjoy seeing the transition from actions based on fear to actions based on bravery in these situations. Keep it up.
Consider dropping stalking her on social media. I often choose to unfollow rather than unfriendly people if I don’t want to see what they’re up to but don’t want to make a point about not being their friend. I don’t think any good will come from stalking your ex online.
FWIW, I have no problem with someone being on the dance floor at any age if it makes them happy and they aren’t breaking any commitments.
