I think in this situation - you should deal with him as if he were not ill. It would be one thing if he was kind caring and all that was missing was sex because of his illness.
But it sounds like that is not the case. If he were not ill, would you stay with him?
Another alternative because he brought it up - is to being up front with him. Tell him you do not seem to really care about me as a wife - not just the lack of intimacy, but the lack of not wanting to do anything about it; you also do not show you care for me as a partner in any other way- lay out the examples including this lack of gift/caring more recently. Tell him you cannot live this way. If he wants to live as roommates due to needed help with his illness you would be happy to do so (if you would be) however, you will live just as roommates and not as a couple - freeing you to have another partner.
It sounds like he might be guilting you to stay with him and care for his health.