I'm going with the minority response. While good manners would dictate that a daughter-in-law should attend, you are talking about people who are lacking in good manners, and, quite possibly, good sense. You mention that the cops might have to be called. That sound to me like there's a real risk that someone will be assaulted. The funeral is not going to be a dignified, respectful affair, in that case.
I heartily recommend that you contact the funeral director so that you and your wife can have a private goodbye. You can read eulogies, poems, sing songs, whatever will make the ceremony meaningful for you, and will make you feel that you honored your father. Then don't put yourselves through the hooplah. You can stay away, or attend by yourself, whatever feels right to you. You can host a reception on your own for those relatives that aren't judging you, so that they understand that your wife's (and, possibly, your) staying away had nothing to do with a lack of respect, but that you wanted to diminish the drama.
Somehow, I think that your father will understand.
I'm going to go along with Jocelyn.
And I'm going to suggest that you look through the list of other family members and see if there are others that you could invite to join you at this private memorial service. For the emotional support, the company in grieving, and the public-relations aspects.
And then decide if perhaps you simply want to make it known among the greater family that you had a private memorial service (for the sake of your reputation among the larger family), and just skip the one your brother attends.
I would also suggest that you visit your dad at times when the siblings aren't there, and suggest that he arrange with nurses, hospice workers, etc., for there to be some times for your wife to visit her beloved FIL when there are no siblings there.
And then you can quietly make this known to other people.
If you decide to both go to the funeral, etc., you don't have to join in the nastiness. You can sit on the other side of the church/room; walk away when they approach you; spend your time with people who are pleasant to you.
This is a situation that absolutely calls for the cut-and-paste. If anyone approaches for drama, you both say the exact same phrase: "It's an emotional time; I'm sure we'll all miss Dad." Even if they're saying, "You're a drunk, and you don't belong here."
Decide that you aren't going to bother "defending your honor" from them, because they are not in a position to BESMIRCH your honor. Or your wife's honor.