This is common in a divorced family. Whatever the issue is, you have to emotionally distance yourself more from the friction between your parents. And as a side note; it isn't very healthy for a teenage boy to be "best" friends with his mother. Especially given how hedonistic you have mentioned your mother is in past postings.
When I was about 9 I told my father that I wouldn't go on a visit with him because he wouldn't stop insulting my mother. I am glad I did this, but I haven't seen him since that day, and I am almost 33. He was wrong, but in retrospect I would have handled it differently. You are old enough to understand that your father isn't perfect. Try to focus on his positive aspects and forgive the negative ones. Parents are human, they sin and have insecurities. Try to affirm that you love and respect him. You aren't responsible for his behavior, you can't make him change. Pray for him and show him that you love him as he is, not as you think he should be. You have mentioned a great deal of frustration with both your parents behaviours in the past. They won't change because you do or do not do certain things. They have to desire to change. And whether they change or not, they are still your parents and you will/should love them anyway.
Good advice. I especially agree that it isn't healthy for children and parents to be "friends," in the sense that parental authority is compromised and respect is lost. But often times when marriages are falling apart, one parent will try to become their child's buddy and the other parent becomes the "bad guy." So do be careful about this.