Have you communicated any of this to him? Why didn’t you make plans for yourself or ask him what if he could include you if you know he gets his son on holidays? Or if you didn’t know, why didn’t you ask him? He to,d you months ago, and you didn’t make plans. Right? Am I confused?
I think this was a test to see if he would include you and he failed that test. If you’re looking for a very attentive partner, it’s probable or possible that he can’t give that, but have you told him what YOU WANT or are you not communicating with him and just expecting him to read your mind?
Be single and move on if you’re not happy with him but if you aren’t communicating your needs the only person to blame really, sad to say, is yourself.