I would talk with a DBcoach. To me you care about your M and family or wouldn't be here. Your wife is acting out and from what I've read, you have some hope and need to proceed in the best way possible. Reread and concentrate on Sandi's list.
You're doing some tough work, Bunches. Reflecting helps us to see ourselves better. It was a difficult time you were going through with your dad and stress causes us to latch out and say things we wouldn't normally say and do during other times in our life. During this time, it appears, your W kept silent and rather than expressing how hurt she felt, she decided to act out in a bigger way. At least you can recall the car ride. My H, soon to be x, has developed amnesia on a need basis and it's almost chronic when he's hurtful, during stressful times and not.