How do I ignore my ex friends opinions?

I broke up with my ex. He was abusive but we ended on good terms. His girl friend posted on Instagram that I was full of myself for leaving him. I have not and will not respond back to the negativity. I have not mentioned any petty quotes over Instagram about my ex either. His friend also copies me, which is weird. But she posts photos almost immediately after I have, the exact thing. For example, I posted a piece of cake on my Instagram, and she did right after, I posted myself getting my nails done, and she also did moments later, I posted a picture at the gym and she did immediately after, I posted my hair straightened wearing a cap, and she did the same. I just find it odd and creepy. Is it rude to block her? I need some advice