"Can they take our refund?"
Probably yes. It depends on all the details. The bulk of your refund probably comes from the Earned Income Credit and Additional Child tax credit. Although those refundable credits are based on "your" child; they are also based on your husband's earned income (SSDI while potentially taxable, is not earned income).
All you can do is submit the Injured Spouse form and hope for the best. Filing separately will not help you and would most likely hurt you worse.
