Your self preservation matters. As aching as your heart is going to feel, watching his life moving forward unfold as you describe via social media cannot possibly feel or be a good thing. No matter how mature and adult one could possibly try to be, that's not good for the soul. Of course it raises your anxiety. Of course it hurts.
I'd ask-you don't need to reply --I'd ask myself if this from him wanting to maintain a friendship whilst sharing of these life experiences about keeping your best interests in mind? I wouldn't expect him to stop being himself on his social media. It's the telling you he doesn't want to lose your friendship while sharing details of his love life that are not with you and how you may feel in mind.
It's a selfish game in a way on his part.