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.

I'd suggest contacting a Veterans Service Officer to see about filing a claim with the VA.
"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.)