As long as you are not married, or holding yourselves out as married (which can be things like using his last name, having joint accounts, etc.), then your income should not be considered for Social Security benefits such as SSI.
This "answer" does not constitute legal advice and does not establish an attorney-client relationship. It is meant for general information purposes only.
His living arrangements will be considered but since you have kept everything separate it should be ok.
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Your income should not affect his disability. Unless he is being reviewed for SSI (which is income based and house hold income matters), but then the fact that he owns a home and land would affect whether he qualifies. Your income would count as house hold income if he is getting SSI. As long as he is receiving SSDI, then it shouldn't matter.