Ask HN: Legal action against former employer

A former startup employer screwed me big time on my equity portion. Am founding engineer who created their valuable IP and led most important team. Was essentially forced out of the company too with their legal team sending warning letters to a competitor about hiring me.

Has anyone had to litigate against a former employer with an equity dispute, and have a lawyer to recommend? The startup was in California but the buyer in EU. Not sure if need to seek a lawyer in EU.