So sorry to hear this has happened to you.
Do not entertain the thought that your weight is the root of this for even one second. Do not entertain the idea that losing weight will make any difference to this.
It is not about your weight. This is a man who for whatever reason, is having a crisis about your relationship and himself and doesn’t know how to handle it or take responsibility. He is trying to shift the burden onto you and make it about the way you look, and about what you do and that YOU have to save the relationship. This is all bullshit and anything you do won’t make any diffference, because this has not been caused by you and you can’t save it.
Either he has met another woman, or is possibly gay and unable to acknowledge it to himself, or is having some other kind of crisis, but he is in a crisis and trying to offload the burden to you.
Sadly, this relationship is highly highly likely to end. He probably isn’t acknowledging that himself at the moment and perhaps is deluding himself that if you look different everything will be okay, or actually knows it’s not about that at all and is therefore being extra cruel by saying it, when he knows it’s not the case….but he’s too cowardly to tell you the real reason, if he knows it.
And then to continue as if nothings been said..so odd and also manipulative. You cannot drop a bombshell like that and then pretend everything is normal.
He has called the whole basis of your relationship and physical attraction into question. He has deeply insulted you and cruelly said it’s all down to you and nothing to do with him, when the whole thing is down to him.It’s intolerable to do that to someone you are married to.
Absolutely don’t consider losing weight or talking to him about things that can make you more attractive to him.
I would be telling him that you are horrified by the conversation he had with you. I would tell him that you are exactly the same person you have always been and any issues are fully in his court. I would challenge him to be honest with himself and to give you courtesy of being honest too - is there another woman, is he gay and unable to acknowledge it, is he having a crisis. Tell him there is only a glimmer of hope if he is able to be honest and if that’s not possible, there is zero hope. I’d tell him that he has 24 hours to think about the explanation he wants to give you and if he cannot, there is nothing to work with and you’ll be expecting him to move out. Make clear this isn’t his house, but yours and if he is ending the marriage, then he must go. Stress that you have always looked as you do and will not be taking steps to change it in light of what he has said. Stress again you require honesty now for there even to be a glimmer of something to work with. And if he can’t deliver that, it is over, and you expect him to reflect on what he’s said to you and to understand why that is the only way.
Then give him the 24 hours to think about what he wants to say. Go and listen to what he says then, and then tell him you need some time to reflect and will get back to him. Don’t be bullied, made to feel fat or ugly or at fault. Don’t be emotionally bullied.
I do think it’s likely to be over. There is just a tiny chance he is able to tell you that he might be gay or he’s seeing someone else or is attracted to someone else, or something else…which then gives you something to work with, if you want to and he wants to as well. If there’s no honesty that this is all from him snd really nothing to do with you…there’s no hope I’m afraid.
So sorry.