What kind of subsidized housing is it? Is it traditional public housing, the voucher program ("Section 8"), or assistance through HUD's multifamily programs? Let me now and I can give you an idea of where to find rules and policies pertaining to the program.
This kind of offense is not automatically cause for termination of assistance (but repayment will be required). As others have noted, you made it worse by certifying that you were not receiving cash aid. If you neglected to report an income change in a timely manner it could be assumed that you simply forgot, but it's more serious when you have made false statements.
For most HUD programs, the subsidized family share of rent is about 30% of "adjusted income." If you started to receive $200 per month in cash aid, your rent would increase approximately $60. So it's never a good idea to conceal income since you're expected to pay such a low percentage.
Is it likely I'll be arrested for this?
Highly unlikely if the amount is as low as you estimate. The local prosecutors usually have dollar thresholds for fraud charges.
is there any chance it could make a difference, or by some miracle I could work things out with the property managers
Depends upon the type of subsidized housing.
I'd recommend that you report the income right away to limit your financial liability as much as possible.