<human>: I'm supposed to stay with the future in-laws for a few days before Christmas as a visit, and at that time we'll be letting the family know that we're getting married next August. This would be a great time of celebration except that my mother in law is a gigantic bitch. 

The week we got engaged, she sat me down and told me they wouldn't be paying for *anything* with the wedding because no one helped with theirs (they were 10 years older than we are). Sure. Fair enough, except that she then started making demands about who should be invited, saying that the 3 hour drive to the destination we wanted to hold it was 'a lot to ask' of that side of the family (it's 20 minutes from where we're living, and 40 mins to 2hr for most of my family; no one else has complained), telling us what we should have to eat at the reception and generally just being a pissant. Is there any way I can tell her (bonus points for nicely) to STFU with the unsolicited advice? 

Secondly, fiance's brother is 26 and a horrific coke addict. He's got narcissistic personality disorder and I have witnessed several occasions, one terrible one, where he tried to kill the family. My fiance ended up choking him out on the porch and locking him out until the cops came. Fiance's younger brother, 19, and his parents have said that if asshole Mcgee is not invited to the wedding, they won't come.

We on no uncertain terms do not want him at our wedding or around any of my family almost purely because of the risk of violence and the fact that he can't keep his mouth shut. We've made our guest list; how can we let the rest of the family know that he is not included on our day?

Could you distill the essence of the text into 1-3 sentences?
<bot>: how can I get through 3 days with my unwelcoming in-laws without causing drama and still be able to enjoy the planning and day of my wedding?