Hi again Lostallalone,
Well, individual counselling is for you and you should find a counsellor that works for you. I agree that the spiritual bypass (forgive and forget while not doing any actual work to address issues) is not a great idea. Also, not all Christian counsellors will advise you to do that so don't count one out just based on them being a Christian. Evaluate them as individuals.
It seems like you were put in a difficult situation as a child, caring for your mom with out a lot of support. It actually does not sound awful that you felt relief when she died, it sounds normal. I'm sure that relief was not the only thing that you felt. I hope you also felt some sort of good feeling that you were there for your mom when she needed you.
You have clearly figured out that the relationship you are in isn't working and that how things have been isn't just "how it is". You have choice, so does your BS. The relationship does need work, but right now I would focus on fixing you and figuring out your whys and also figuring out what you actually need. I had a bit of a similar problem, not with a verbally abusive BS but rather my view of what love and relationships were supposed to be like was very skewed. I viewed them as being largely transactional where each person was supposed to make sure that they "got theirs". It was much more about "what can I take?" as opposed to "what can I give?" and I didn't have any qualms about lying or withholding information or manipulating to make sure I "got mine". During my big brain rewiring project I read this definition of love when I was reading Brené Brown's book "The Gifts of Imperfection" and it really spoke to me and helped me reorient my views on love and relationships. It was the first time in my life that I could point to something and say "That. I want that so much. That is the relationship I want to build with BS." Here it is:
“We cultivate love when we allow our most vulnerable and powerful selves to be deeply seen and known, and when we honor the spiritual connection that grows from that offering with trust, respect, kindness and affection.
Love is not something we give or get; it is something that we nurture and grow, a connection that can only be cultivated between two people when it exists within each one of them – we can only love others as much as we love ourselves.
Shame, blame, disrespect, betrayal, and the withholding of affection damage the roots from which love grows. Love can only survive these injuries if they are acknowledged, healed and rare.”
As far as dealing with your BS goes, even if she treats you terribly, remember that her anger/contempt is most likely coming from a place of pain. It is difficult when you feel you are being attacked but try to have compassion for her. It will become easier to have compassion for her as you develop compassion for yourself. If you find yourself unable to have compassion for her when it's happening, then focus on having compassion for all the other people in the world that are going through something similar at that moment. With 7.5 billion people on the planet, you know they are out there. You can use these difficult experiences to foster a sense of shared humanity and connection. The details of our situations are different but we all experience pain. We all experience loneliness. We all feel lost sometimes. Focus on breathing in the pain of everyone going through what you're going through right at that moment, and then breathe out relief for them. It sounds counter-intuitive I know, but it is a very powerful practice.
You have a lot of studying and learning to do. Get started now and future you will be thanking present you for doing so. A person a lot smarter than me once said "If you want to understand the present, look at the past. If you want to see your future, look at what you are doing today." The choices we make in the present moment build our future.