My maternal grandmother is mentally ill, however, she is a "functioning" person. She tends to start fights with everyone in the family. She hates men (and boys) and says crazy things like she thought my 3 year-old nephew was trying to murder her, and when he was 8 and got in trouble at school, she asked if he had gone to prison. My mom feels obligated to her, and she really wants me to invite her (my mentally ill grandfather is on the agreed "Do not invite" list). I do not want this woman at my wedding. I can see her throwing a tantrum or saying something unthinkable to someone, including my sweet nephew or even my FH. I told my mom I would consider it. My maternal aunt agrees that g-ma should not be invited. I don't want to make my mom feel bad or put her in a place of telling g-ma that the invitation is NOT in the mail. What should I do? Can I get away with not inviting and welcoming a sociopath to our wedding?