[shorod]

Unfortunately, if the contact for the relay corroded bad enough that it broke off, you likely had a poor connection with that relay terminal, and the terminals have overheated and weakened now. So even if you were to get the broken piece out, you would not get a new relay to make a good connection and would have the same issue in short time.

You might want to check NHTSA's website to see if maybe there is a recall for this existing on your car due to the safety risk this could provide (both from visibility and from possible fire risk from the poor connection), and if not, your best bet might be to source a replacement fuse box from a salvage yard or the dealership.

-Rod