is she wrong

Okay I need advice my sister still has my ex on her fb and she told me sometimes I want to like pictures of her and her gf and stuff she post about her gf so I did t say anything today I was on fb and you know how If someone likes something it pops up on your page well my sister liked my ex post about her new gf like idk I'm kinda mad right now do you think she was wrong for liking the post because I do. No my sister don't even like my ex through the whole relationship I was being played and my sister knows this and it's funny because if I post about my gf my sister doesn't like the post she don't even like our pictures