Not Inviting Certain Members of the Family

Although I'm not married, and I won't be getting married for a couple of years, I was thinking about it and there are some conflicts in the family.

1.( Should you tell a family member you're engaged if your not inviting them?

-My mom is a raging alcoholic who practically abandoned me to my Grandma when I was 12, which was the not the first but the last time she abandoned me (She dropped me off at my Aunts when I was 9 and signed over Power Of Attorney because her boyfriend at the time told her to do so because I was causing problems in the relationship. Decided she didn't want to do that and did it three year later. I grew a hate for alcoholics.

2( Is it rude to invite one spouse and not the other?

-My Grandmother's third and current husband (Have been married for two years as of March) has made me feel seriously uncomfortable when I lived with them. He would call me hot and ask for a "hug" then kiss my neck and slap my ass when my Grandmother wasn't around. Now, my grandma is my best friend and I know her well enough to know that she wouldn't believe me and it would ruin our relationship if I told her what her husband has done, so I just moved out and let it go. Despite letting it go, I don't want him there for my big day, for the obvious reasons. He too drinks a lot. His excuse is "He's a Mexican." And I wouldn't put it past him to show up at my wedding drunk.

There really is no guidebook to "What to do when your family is fucked up" so, what would you guys do??