That's truly horrific and disgusting. Such mothers are like the wives of the Nazi commanders - they knew their husband was killing people and each such wife welcomed each such husband home and made him comfortable. To me, the cure is to get away.
Some people just are irrdeemable monsters and they eat up your love until there is nothing left of you. I speak form personal experience. Don't offer them your other cheek - just leave.
There was the case of the West family, where the mother enticed young girls into the car her husband drove, then they both tortured and molested them, then killed them. They did that to their eldest teenage daughter . Sorry to say this about your mother but some people are beyond redemption, especially when they have shown no remorse. They deserve not your love, but your shit. I really am writing this to support you and urge you to disengage. You will thrive once you have cut ties with what brought you down and broke you to pieces.