I'm thinking of remaining somewhat unattached from my dad
Why are you unattached from him to begin with?
I hate him for abandoning both my younger brother & I when we were kids.
I'm sorry to hear that happened to you and your brother when you were younger. Family relationships are not always healthy, but you should be willing to give your father a second chance to be part of your lives.
I don't know that I want to forgive him. He was a real asshole.
What your dad did was wrong but excluding him from your life is not correct either. Speak to your father and tell him your feelings. Work through your pain so that you can be a family again.