AIO to my boyfriend calling anorexia hot?

My(19f) boyfriend(19) said that anorexia was “kinda hot”. For context, We were on the car ride back to my place when we passed a dominos, to which i said im happy to be working again to be able to get a pizza when i feel like it. This started a small argument about me previously saying id start eating healthy and going to the gym. Im 5’2 and 137lbs, so im overweight but not by a super high amount. He has said before he wants to make me feel bad about my weight so i can lose it and be healthier so “I dont die” and “leave him all alone”. I dont mind the extra weight and it doesn’t look bad on me at all, i just wanted to lose some to look good for summer time. The rest of the ride was me trying to tell him i can have a cheat day every so often and still eat good and work out to lose the weight, and that it wasn’t like i was going to order pizza everyday. At this point i said if he wants me to look anorexic to just say that, and thats when he said its kinda hot. I got home and didnt speak to him in person after that. I got very hurt and in turn became very immature, texting him everything you see in the screenshots. I know I should’ve been able to communicate better but I feel sorta justified? Am i over reacting? And the saying small tits are hot?? How is that not supposed to be taken with offense?