Married for 12 yrs in active duty..now he is retired am i entitled to his benefit?

It depends which benefits you are seeking. Military retirement may be considered part of the marital estate and you can seek a portion of such pay. However, if you have a retirement account from your employer, that account would also be part of the marital estate. Once divorced, it is unlikely that you would retain military spousal benefits (i.e. medical coverage, base privileges). Under federal law a former spouse of a servicemember only retains entitlement to military benefits and installation privileges if they meet certain criteria, such as being married to the servicemember at least 20 years. If you are looking for health coverage, there is a continued health care benefits plan that you should look into, however it is not free.