I'm going to pressure her to unfollow her ex.
Does she want to get back with her ex?
Yes and she said so in a previous conversation.
You can't control who people are in a relationship with. It's her choice who she wants to engage with on social media.
I will just wait for my chance and use emoticons to make her feel guilty back into my relationship.
That sounds like a really immature way to handle the situation. She can be friends with  an ex if she chooses. Maybe you can directly communicate with her how it makes you feel?