Am I overreacting about this? Or should I think about some things?

Jazmyn
So earlier this week I went to the doctors and I found out that I gained 20 pounds over the past year mainly because I've been in a relationship. So I told my boyfriend and at first he seemed supportive of the fact that I'm going on a strict diet. So I met up with my boyfriend at his job at lunch and we were having a good time and all of a sudden he starts bringing up my weight and saying how 20 pounds is unhealthy and I'm telling him that Im already back to my workout regimes and my diet. Mind you he isn't in the best shape himself. As I'm eating I'm really feeling like he's ashamed of me that I gained so much weight and he's telling me that I look fine and it doesn't look like I gained any weight but then a minute later he starts jiggling my arm fat and he's like damnnn and of course I'm in my feelings cause I gained so much weight and he's telling me to lighten up and that I'm overreacting and that I'm making him feel like the bad person. So he's pissed. And I'm trying to tell him that I'm so hard on myself and disappointed because 2 years ago I had a eating disorder and that I would work so hard at losing weight that I wouldn't eat anything. And he starts mocking that I had it and saying it's impossible that I had an eating disorder cause I would still have it til this day. So now I'm conflicted am I in the wrong here? Or do I have the right to be upset?