I too am really pleased your Dad has not let the cult get a complete grip on his personality or his thinking. With your Mum it is to be expected that she feels the situation very keenly, it is as though her child has decided to kill himself, that is how she feels.
A poster above said, "Love never fails", which is true, it is people's failure to react as they should to love that is the problem.
Keep telling them you love them, and will be there for them, whatever happens.
I have told my old Mum this, and also said that I " haven't left the truth, I still love the truth, wherever I find it", which I think she knew was a barbed comment, but we have had a normal family relationship ever since, we just don't talk religion, suits me.
Well done, you have made your life much more free and much better by what you have done, been honest and yet loving.