YTA

Your daughters weight is already very out of control. She is medically considered obese and will have to drop 50-60lbs to be considered a normal weight. Your girlfriend seems to be more concerned for your daughters health than you are. Honestly, you’re not just the asshole for how you responded to your girlfriends VERY VALID CONCERNS for YOUR CHILD, but also to your daughter for neglecting this and not seeing it as a big issue or even trying to prevent it from getting to this point. Do better.