Another ex dream

Date: 12/28/2016

This dream i had last night. i was with all my mates, we was in our usual "hang out" spot and out of nowhere my ex came with her boyfriend and best friend. we had a little conversation to be polite and then the best friend left. So, we decide to leave. As we are walking away i turn back to see my ex kissing her boyfriend, and afterwards smirking at me. My ex will often do this in real life, not with kissing though. She will often find ways to wind me up. Does anyone have any advice as to how to ignore her?