Most Helpful Guy
Because they are excited and trying to move on, he probably is not thinking that it will hurt you. I did the same last year after my fiance and I split. At the time I was still in the numb phase about our break up and I just was not considering how it would make her feel. I didn't wake up till it was too late and my insensitivity killed our friendship. If you say something to him just explain it as nice as possible and remind him why you are still friends on social media is because you care enough to stay friends. If he cares enough to stay friends he should consider being sensitive in the future.
Most Helpful Girl
im goin through same my ex got with a girl a wk after we broke up from out 7 years together in a relationship on social media and Twitter pics all over i aske him not to but they both did it more i had to block.. dont look dont get obsessive lookin at his fb Twitter i made that mistake.. they are pure rebound because if they was happy they would keep quiet but knowing your lookin and makin you jealous just makes them thrieve.. best thing for you is to NOT react go into no contact and watch it all fall apart x