Your question is “Am I being selfish in not losing weight?”.
No, your weight is your issue and if you are ok with it then so be it. Also it cannot be selfish if you truly ‘can’t’ lose weight because of day to day issues. You can only be accused of being selfish if you have a choice over whether you can do something or not, and are choosing not to lose weight. You state that you actually can’t, so selfish doesn’t come into it. I personally think it is not easy, in a busy lifestyle, but not impossible, for anyone to lose weight except in medical/ prescribed drug situations. So ask yourself honestly if ‘can’t’ means ‘don’t want to.’
However:
Whatever the side issues of whether it is healthy or not, or whether your husband is being shallow or doesn’t really love you if he doesn’t appreciate you whatever size you are, are neither here nor there, since he has been honest enough to say what he really feels about it. As far as your marriage goes, what is ok with you and him is your business and whatever we think of his views, they are stated clearly.
He is using strong words, OP.
“Save the marriage “
“doesn’t find me attractive.”
“can’t live in a sexless marriage.”
This sounds like he feels that your marriage is on the brink. He has been honest and communicated his needs in your relationship, he has used “we” in order to get on board with you and do it together, he has not belittled you or used derogatory language.
We can’t help what we do/do not find attractive. It doesn’t mean we don’t love someone if we start to struggle to find them sexually attractive at a noticeably different size to the one they were when we were first attracted to them. He’s tried to say it as nicely as possible and it’s far better and healthier in any relationship to be honest and face issues rather than just leave without giving your partner a chance to decide whether the request is reasonable or not.
He loves you enough to tell you, he loves you enough and wants the relationship enough to change and help you change (if you want to). If you don’t want to, and he continues to struggle over sex, your marriage will end, whether he loves you or not. I think he does.
Men quite rightly get handed their arses on a plate on MN for suddenly leaving partners, or having affairs without telling their partners what was wrong and giving them (and the relationship) a chance to decide whether or not to address the concerns raised. If your husband had suddenly left you or found someone else for sex without having let you know how he felt before this, without having given you a chance to decide whether it was reasonable or not to meet those needs, he would get rightly slated.
Whether he’s being reasonable/ unreasonable here, whether you are being selfish/ not selfish here, could be debated all day. What is obvious, though, is that you are in a sexless marriage, he doesn’t want that (not many do) he has stated why he finds it difficult to initiate sex, he has stated the marriage is in dire straits and needs saving, and if nothing changes, then it looks like your marriage in all likelihood will be over.
So, selfish or not isn’t the issue. Do you want to be married to him or not?
This isn’t going to be popular but hey ho:
Losing weight unless you have a medical condition or are on medication which makes that difficult, is not impossible for anyone, in any lifestyle.
Otherwise everyone who has the same lifestyle issues would be overweight. Not everyone in similar circumstances is.
If we are not physically impaired, and have ten minutes to sit and watch tv, or to scroll down our phone on social media 😉 we have ten minutes a day to go for a brisk walk or jog on the spot. Even ten minutes daily over time makes a big difference. Cutting out one snack a day makes a difference over time. Big changes are hard to maintain, smaller steps one at a time are easier to do. And they work. But it’s a free choice and there’s no shame in not doing this and being happy as you are.
The choice is yours, OP. It’s not selfish to not want to lose weight, no, but it’s very clear that it might end your marriage if you don’t, whether we think your husband is right or not. He can’t help what he does/ doesn’t find attractive any more than you or I can. I think he loves you and I like his honesty and desire to openly communicate and save your marriage.