I admire the clarity and depth of understanding you bring to the situation. But your family is not likely to be the source of your healing. They seem to still have significant issues, and there is difficulty between your fiancée and your father. Tolerating them from time to time isn’t the same as healing from your childhood experience. You need a different plan.
I would highly recommend group therapy run by a skilled individual. At its core group therapy is a correction of the pathology begun in the family of origin. Healing the issues you are carrying with you from childhood should be the prime objective. Once this has happened you will be in a much better place to decide how to handle your family.
As a child, you needed something they were unable to give. Don’t make the same mistake again. Heal yourself through the group process first,then see where you are at with your parents.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral