That's tough, Ker2See. It's painful when we feel like we need to make the kinds of choices you're facing now.
Your father, as you probably have already guessed, is very strongly co-dependent. Having a relationship with him, at this point, will likely mean that you will also have to involve your mother. Until he gets help for himself (which, if he is like my father, is unlikely), he will continue to appease her, even if it's at the expense of his relationship with you. It's probably very painful for him as well, but he has to live with your mother and may feel that he needs to keep her calm for his own well-being.
Through a few communications with both parents, I had finally concluded that I needed a break - either temporary or permanent. This, of course did not go over well with my dad - he's sucked into my mom's world pretty deep after 45+ years of marriage. He is basically confused and claims to have no clue about what has happened to our relationship. So, in fairness, I feel obligated to open the flood gates and let the river flow.
My feeling on a break is that it doesn't need to be permanent. I know where you're coming from--my father is also very enmeshed and I've spent many T sessions talking about how hurtful my father's co-dependent behavior has been. Taking a break helped me to work on myself and gave me the space that I needed, but didn't know that I needed.
What I'd suggest you do is continue to work on yourself and decide what you can and cannot live with when it comes to your mother. How much interaction you have, how often you see her, how you respond to her behavior. From there you can figure out how your relationship with your dad comes into play. Hang in there.