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.