You cannot use the home you live in to provide financial support for an immigrant.
You will absolutely need a joint sponsor (or ideally, an adequate salary) in order to petition him. The process can take up to two years once the petition is filed, so you’ll have plenty of time to plan for that.
In terms of not having money/time to spend time together in person, unfortunately that won’t fly for immigration. Depending on his citizenship, I’d strongly advise you to delay filing until after you’ve spent time in person, if you intend to marry on the first visit. Online time “knowing” someone doesn’t count. But again, due to the length of time before a visa would be issued, you would have plenty of time to work on the marriage bonafides.
What is his country of origin?
Sorry to hear of all you’re going through. I know how hard it is to be a caregiver for someone you love. Please take care of yourself.