Hello,
It seems as if your friend was trying to protect his relationship by cutting communication with you. Your past experience (i.e. hookup) and re-connection might have sparked insecurity/distrust in your friend’s partner. Of course, it’s rude to send unnecessary messages to you or any other person as this should have remained between the two of them. You say you feel “rejected, betrayed, and angry,” but nobody is making you feel this way. Look deep into yourself and ask why you are really feeling that way. Nobody can make you feel anything you don’t want to. Friends re-connect and disconnect all the time, so maybe you guys can connect at some point in the future. I would say process your feelings on your own and try to respect your friend’s decision.