It really sounds like your mother played a huge part in why you didn't go. Their sour relationship made him not want to cause drama. If anything that's on both your parents. You were 14, a good mother would have helped make that happen. It isn't just your dad. You said originally that this incident made a great relationship into a bad one.

Of course your stepbrothers were there, because it was easy to coordinate that. Whereas your situation had drama associated with it. Why did your dad feel he couldn't bring you? Why didn't your mother make it easy for you to go? Advocate for your needs? This isn't so black and white.

Don't kick your dad out of your wedding. That's horrible when he so clearly cares. You're holding a massive grudge with a father that is actually trying. A wedding should bring you all together, it's such a shame to use that day to say fuck you to your dad. Have both your dads walk you down the aisle. All this drama and resentfulness will all be regretted later in life. It isn't worth it.