Lawyers are how professional adults resolve things amicably. Having your lawyer handle it doesn't mean the interaction isn't amiable, it means that the person amicably resolving the situation is both aware of their legal rights and responsibilities, and that the principal is savvy to the concept of liability because they have a professional advising them.

Almost all things resolved via lawyers are resolved professionally without a trial or a fight. This is literally the primary function of lawyers: to interface with the other party's lawyers and find a mutually consensual resolution to a problem without compromising your own rights and entitlements.

Showing up without a professional sends a clear signal to the other party that you're not interested in doing the minimum to protect your rights and ensure that the other party doesn't steamroller you, which incentivizes the other party to trample your rights and steamroller you, because there's a likelihood that you haven't been advised of your rights in full and don't have an immediate and convenient path to enforcing your rights against the counterparty. It's bush league.

Get a lawyer. Have the lawyer handle it. "Handle it" doesn't mean an immediate lawsuit, it's simply the way professional organizations indicate to other professional organizations that actions have consequences. No lawyer means you don't intend to cause them any consequences, which means you're ignore-able.