Short answer, no you cannot sue the military for sexual assault/harassment. Survivors just recently lost a suit at the Fourth Circuit based on these types of claims.
http://www.ca4.uscourts.gov/Opinions/Published/121065.P.pdf

I'd suggest contacting a Veterans Service Officer to see about filing a claim with the VA.
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"When we go into battle, I will be the first to set foot on the field, and I will be the last to step off, and I will leave no one behind. Dead, or alive, we will all come home together." LTG Hal Moore, Jr., USA (Ret.)