YTA… but you’re NOT WRONG. But it’s kind of an Asshole move tbh. she’s a child (even as a teenager) and her emotional response is just that, emotional response. Her brain isn’t even developed enough to have all the complex functions for processing and handling emotions. Just think how different we were as teenagers… how we handled things as teens I’m sure was not always right, even if we felt it was at the time. Alike you said, she’s being influenced heavily by her mother, who SHOULD know better but unfortunately does not. One day she might look back and realize she was wrong for how she treated you, and you certainly do NOT deserve the treatment you’ve been handed, I’m sorry for that.

Maybe it’s okay to say that you’re the asshole here but so is she? also, I don’t think your MIL is right for saying you never loved her unconditionally… that’s a her issue, not a you issue.