I posted "is it reasonable?", let me explain more

I knew it wasn't just me who thought it was wrong. Sadly, I have a history of hate for her. Firstly, I want to state that we have a child together, so it's really tough to just leave him. So about my hate for her, let's get started. I usually went to the store with him, when he was off but they needed him for something. That's where we "met". So she knew about me and our child! Valentine's Day rolled around and she gives him heart cookies with a heart shaped card with (just) his name. He claimed it was for "the both of us", yeah, sure, whatever. I never thought anything of it. One day looking for the baby's teething gel, I moved my magazine and the heart was under it. So I thought "Uhm he said he threw it away". Then I seen the back, and that's when I got angry. Long story short, it said "I'm going to miss you, you're the best! You get em tiger! 😉 Come visit me often! ❤️ (her name)". There was way more to it, but it's too long. I thought I'd never have to deal with her again. But now, he's liking all her selfies and saying she deserves a fucking "💖"?! Like the "💛💙" wasn't enough. She doesn't deserve a sparkly heart, she doesn't deserve shit from my boyfriend! But like he said, I have "nothing to worry about", as he "doesn't speak to her since he left the store". Obviously bull shit! I just wanna throat punch him. 😡

*Edit: No we are not teenagers, we are young adults. (Early 20's)*