employer claiming my side project IP — what are my options?

I publish illustrative scenarios prepared by my practice. All participants and conversations are fictional. The fictional posts are not posts by real users, accounts of client experiences, or reports of actual results.
Illustrative scenario prepared by my practice.
For informational purposes only. This is not legal advice. Laws vary by jurisdiction. Consult a qualified attorney for advice specific to your situation.
Hypothetical question

Quick background on my situation — any input appreciated.

employer claiming my side project IP. I've been dealing with this for about 16 months now and the situation isn't improving.

This involves software/code I developed over the past 22 months. I do have documentation proving my ownership and timeline.

Do I have a strong case? What should my next steps be?

Illustrative response

Have you tried reaching out to your state's consumer protection office? They sometimes have free resources or mediation services.