You can be a representative payee without jeopardizing your own benefits. If you misuse her money, it is easy for SSA to collect the misused funds from you. You need to keep good records and not just hand her money. I would open a separate checking account and write checks to pay her bills and do very little business in cash. Protects you. Protects her.

I am a bit concerned that you first referred to this person as a friend but then later corrected it to wife. Now you don't have to be totally honest with us here, but you do have to be totally honest with SSA. That response bothers me. Do the two of you live together? Is there SSI involved? It matters for SSI. It doesn't matter for SSDI. As payee, you should know the difference.