Can't choose your family?

I have a sibling, M, that had drug problems in the past. M had very serious problems in the past that ruined a promising professional career, landed M in legal trouble and resulted in M moving a few states away. In normal families this sort of living arrangement is fine. My family is nowhere near normal and we believe that in order to be a good family member one must reside on the same street (which makes me a black sheep of sorts). Well M got married this week to M, another fellow drug addict. More specifically, M&M (I couldn't resist) did it, sold it and got clean together. However M, my new in-law has been drinking. The wedding was in another coastal state all together. It is a beautiful, rich location and only a few of the family could afford to attend. My mom and sis went. They had a great time despite M's (the in-law) and my mom's hate for each other. They don't hide it. Well, M drinks, the night goes from bad to worse culminating in a group fight, physical and an overdose of pills. So M (my sibling) is in a state on a honeymoon two states away from where M lives while M, the in-law, is under a 72 hour suicide watch. I am thinking to myself how sad this is when my mom calls. She is exhausted from the ordeal having just returned today. She says she knows it isn't "Christian" of her but she wishes that M (the in-law) had, "done the job right and killed M's self" I told mom that was the worst thing I had ever heard. Mom's first hubby was an addict and sells cans now to get high. She has little tolerance for addiction. She married my dad. He was not an addict. He was brutally bipolar but mercifully only unleashed in on her, not us. Sorry for her, but all in all, good childhood! =)
So I am thinking to my romantic plans to remarry C when he graduates in 1.5 yrs. Mom will never understand. She wants my siblings brand new spouse to die. I said that M is sick, needs our support and sibling will need us. If M hears her ever say something like that then M won't come home for Christmas, to say the least. I realize that this can be complicated bc of the Ms but to protect privacy, and surely somewhere the story is in print, I have to use initials. Why does the attitude towards addiction have to be so criminal and dark? I realize that it is a sad ordeal, but so is cancer and every family in the US has an addict. Why would mom say that "M is bad. M needs to die."? How can mom say that? What does that mean? That my sibling is stupid and doesn't see in the spouse something wonderful and someone to love? M (the spouse) is ill. Anyone that would try to kill themselves is ill. I told mom this. She wasn't listening. I am sad about this. I didn't know that my family was this small minded or ignorant. About every third person is addicted to something in the family and everyone sticks their head in the sand. What is a daughter to do? I guess I need to move my family somewhere near the sand (I have always pictured myself near the beach) and raise my kiddos in a more tolerant atmosphere. I miss my dad so much during these times. My mom is, well, a tad dramatic. It finds her everywhere she goes. He kept her grounded and always showed us the stripped down version, to look at the facts and see the picture. She showed us a tunnel vision version if you will. I miss his words of wisdom and his lack of judgemental bullsh#@. I hope he is speaking to M today. I know that M needs it. M struggled so hard to get clean. I wish M would call me. We have a connection bc of addiction. M struggles with it like I do, though I am not a drug addict. We are cut from the same cloth and maybe mom is more harmful to M now, despite the best of intentions. M doesn't need the pathway to hell paved by mom.