Brand Name / Business Name Conflict - competitor copying my API

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Illustrative scenario prepared by my practice.
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Hypothetical question

Sorry for the wall of text. Quick background on my situation — any input appreciated.

competitor copying my API. I've been dealing with this for about 13 months now and the situation isn't improving.

This involves content I created over the past 34 months. I do not have documentation proving my ownership and timeline.

Should I hire a lawyer for this or try to handle it myself?