Im leaving but I hope I don’t go crazy before I can

Im trying to come up with an exit plan but Im doing so secretly.

My question is for those who have gone through something like this before, how did you stay sane leading up to leaving?

He’s started taunting & pushing me to my breaking point where im crying and yelling at him, he shuts off his emotions and presents himself as very calm and level headed and pulls out the camera to record me.
This is making me feel like he knows im up to something and he’s collecting evidence to show im crazy or something.
He breaks my stuff, abuses drugs, takes my car for long periods of time leaving me trapped at home and no one to call, he calls me a fa***t all the time, bitch, slut, tells me to shut the fuck up and will charge me to scare me. I can go on but there is the gist.

His behavior is becoming more erratic and very mean towards me lately and it’s hard to not react. I don’t have somewhere I can go hangout for a few days, or family I can go stay with.
I know I need to leave, I’m trying.
Just asking how do I stay sane until I can.