12v battery keeps dieing and after jumping 3 or 4 times car stopped moving while driving.

Hello my 2015 prius has 240k miles just stopped accelerating on me while driving. My 12v battery died a month or two ago had left the lights on. I jumped it it was fine then dome light was left on 3 or 4 weeks ago and jumped it again it was fine then a couple weeks ago my water pump or thermostat stuck and has been causing overheating issues but when driving with heater on max have not problems but my 12v battery dies last night and again jumped it ran fine to work then got off and came out to it dead again got a jump and drove about 1 mile and the car lost all power triangle od death light came on check engine light and the traction and abs light s came on pulled over and turned off car then when. Tried to turn it back on git a aux battery low message and the car wouldn't turn until slowly lost all power to display and lights git another ju.p only for it to happen again about half a mile down the road got car towed to my house and when hooked up to a battery jumper tool it started right up and drove into my garage no problem. Is this all just from my aux battery being unable to hold a charge?

 

I have an obd2 and the only code it throws is the p261b or whatever the water pump/ thermostat code is and that only thing in permanent, pending, and normal code sections of the obd2. And only reason it hasn't been fixed yet is because I haven't had the money but still had to get back and forth to work each day as this is my only vehicle at the moment.