If this is happening in the US, then there is definitely a legal action presented by this set of facts . But, here's the reality: even a legal claim will only led to a settlement of some kind.
Here are some of the settlement terms that I would seek:
1. Two year consulting contract at half-salary. Work hours at your convenience.
2. Health insurance coverage for two years.
3. References (written by you).
4. Waiver of all non-compete/non-solicitation prohibitions.
5. One year contribution to all pension/401(k) plans. All stock and options vest immediately.