Thanks for the words everyone

Funny story. My grandfather (well, my half brother's grandfather, so not really my grandfather) recently got remarried to the most evil woman on the planet (we think she's trying to kill him by starvation. She's been married 4 times prior, all husbands died, and within months of marrying him, she started trying to convince him to change his will to leave her everything, but thats another story). Well, I always get a cared and some money from gramps, but this year I just got a card. No big deal though.
The thing that pisses me off, is the card. On the envelope, when someone would just write the person's first name, grandpa's evil wife wrote "Adam Lowe". WHAT THE HELL OTHER ADAM THAT THEY KNOW HAS A BIRTHDAY THAT DAY?!?! Jesus... Plus, when she gave it to my mother to give to me, she said "Here, this is for your son". I dont even think she actually knows my name. Popular family theory is that she filled out the card, lied to grandpa about putting money in it, and purposely gave the card to my mother, in front of grandpa, to throw him off. This woman is pure, unadulterated evil. The card was also signed, grandpa signed it grandpa, as usual, and his wife signed it "Katherine Siddons". At least she doesnt expect me to call her grandma.
I just want to start calling her and politely hint that I intend to kill her. "Gee Katherine, it sure would be tragic if you slipped and broke your neck this winter"