My ex is having sex with someone else?

We dated for over 2 years and broke up about 2 years ago, regardless he's always managed to try and flirt with me and we've stayed friendly after a period of no contact. However recently he tried kissing and tried to take things further but I said no. Then last night I saw he was tagging this girl in some sexual posts and although I don't necessarily want him back, I feel hurt (don't know why because I didn't even want to kiss him when he tried to) and I feel really weird about it. Does everyone feel like this after finding out their ex is sleeping with someone else or am I just truly not over him then?
My ex is having sex with someone else?
Add Opinion