2016 Subaru Outback brakes problems

I exited the expressway. I was approaching a red light. This was where I usually make a right to go home. Obviously I was trying to slow down the car, and I stepped on the brake. And the car did not slow down. I continued pumping the brakes but the brakes would not work. My wife was in the passenger seat, and my mother-in-law was riding in the back seat. As the brakes failed, I continued attempting to slow the car.

I left my home to go get gas a few minutes away. After I filled up at the pump, my car would not start. I tried several times, and asked a gas station attendant for help. He said it sounded like the battery or alternator. I was able to get the car into neutral, and he pushed my car back into a parking spot so I could call someone for a jump. However, within the few minutes of trying to start my car and being pushed, the battery drained so quickly that the car was completely dead and inoperable.