Oh OP your pain really comes across BUT - you are making it all an issue of all the supposed reasons why you are not good enough for him 'anymore' and that just is not what this is about. This is his issue.
It sounds very unhealthy and a lot of pressure (and then twice as much disappointment) for you to be wanting and trying to be attractive for him 'making effort' being slim, being a good wife etc. At the end of the day what has changed is with him and not you. At the end of the day, If he wanted to have sex presumably he would be having it and initiating it, ans he very definitely isn't. He shouldn't be having sex he doesn't want to have and to 'make time for you in the bedroom' would be just that would it not? Would you even enjoy it if he did OP, surely you'd just feel crap and so would he and it would be as a result of coercion. It seems like there is a lot more to this than it all being ok if he would 'just' try and sleep with you. He doesn't seem to want to and you'd be better focusing on the reality of that, and why, and what you will do about the relationship.
The fact he's giving excuses rather than talking about it is also dismissive of you as his partner, and rejects emotional intimacy as well as physical intimacy. I would be considering whether the relationship still works for you OP, rather than focusing what he might need to start to find sex appealing again, it sounds like you do more than enough catering to his needs if you feel like a maid.I would stop doing those things- why can he not do them? The relationship does not sound well balanced and you do not exist to look after and appeal to him.
Otherwise ask him to see a therapist with you? Or a GP, in case there might be more to it and there be a health issue (erectile dysfunction/depression etc) but ultimately these things rarely change.
If he's claiming it's due to mental health but won't seek help, or go to therapy I would plan to leave. I would never feel happy with a partner as closed off as that, it isn't healthy, and there is no intimacy of any kind. It just means he can opt out of anything, cite 'stress' and that's that - it's not a partnership. Think of yourself here OP and how this is clearly affecting your self esteem, is he worth that, when he doesn't make you happy either, as he is.