Hey Afa - I've been away from these boards for some time, but I think I can give you some advice on this.
From my experience family members, whether they know the whole story or not are just too close to the situation to be anything other than completely loyal to their family. In this case it's your Dad.
Your Dad has his own feelings on this and is his own person. Now that you know he has been dealing with his feelings on your M, by venting at your W, you can talk to him about it. Say something about it being good that he is looking out for you, but that this isn't helping your situation and that he can be supportive by just listening to you and not getting involved.
There's no harm in listening to what your W has to say about what your Dad has been saying, but think about what you are validating before you validate what she is saying. For example, you might agree that your Dad was wrong to say what he did and in front of other family members, without validating what he said to be wrong.
What I'm trying to say is don't sell your Dad down the river, acknowledge your wife's complaints about his outbursts, apologise on his behalf for upsetting her and say that you will speak to him about it.
Don't get drawn into what was actually said, that won't help towards your goal.
Bill
Me 34 W 32 D 9 S 6 M: 9 years T: 12 Bomb: 02/11/12 EA/PA: 12/17/11 - ongoing Moved out: Oct 2012 Joint Filed for D: 2/11/13