Slight Irritation

I've only mentioned my biological father in a few previous posts. There's a reason for that. He's practically a stranger to me. I may know history about him, but I don't KNOW him. I don't know what his favorite cereal is, what his pet-peeves are, or where he likes to go just to hang out. I know that he's always paranoid (due to the meth), and I have his handwriting (chicken scratch). The last time I talked to him was somewhere around Christmas or New years. He remarried a woman barely a year after my mom and his divorce back in '86. Years that followed proved to be vindictive, spiteful and jealous of my sister and I. She only thought of her and her only child. I remember at Christmas her daughter got brand new everything, while my sister and I got her wrapped hand me downs. I HATED football! During that whole entire season, I'd take 3 books with me, and I'd sit in my room while visiting my dad's house and I'd read them all. That's when I'd do all my extra credit for school, I had nothing else better to do, while my dad and step mom sat in front the TV. That part of my childhood only turned out to be empty promises and big lies. When I got older, and realized more and more (like them dealing while I was visiting), I stopped going. I hated going down to Boise. I think when I moved to Lewiston, I saw him 3 times. I know he took my mom back to court when I was 16 because he though my mom was telling me that I couldn't go see him. I had to sit on the phone with the judge and explain to him I had better things to do. The judge in turn told my dad that I was 16 and old enough to make my own decisions. Shortly after that, the meth took control of his life and I broke all communications with him. Six years later, my uncle told me to call my dad because he's out of jail and his life was on a better track. I did. I gave him that benefit of the doubt. Like I said, I only talk to him every now and again.
With all that being said, last night my sister called and said that she talked to dad. I guess she's going down to Boise in June to see my brother in laws family, and was going to try to meet up with dad. Great. But what pissed me off about that conversation was that she let my nephew, Cooper, talk to my step-mom. She convinced him that he wanted to stay with them for a week during the summer break. She PROMISED him to go here and go there. It was my childhood all over again. She promised me all sorts of things just so we'd come down, and she'd find some lame excuse for us to stay in front of the TV. I guess she had told my sister that she wanted my kids for a week too. Uumm... I don't think so. They are strangers to me, so I'm going to ship my kids off, 8 hours away from me for a week. Eric even said no. Well, those weren't his exact words, I put it mildly and edited it for you. I just don't see how they would think that would be okay. I know they are "grandma and grandpa" but ... I don't have words to express my confusion. I have given them every opportunity to come up here and spend time with the kids. I have room at my house. I have never denied them that. These are MY kids and it's my obligation as a parent to keep them safe from whatever I feel is harmful. And going to Boise for a week without me being there, I just don't feel that's safe. It baffles me to think that she would think I would be okay with all of that. I'm just not sure if the meth has killed a couple few brain cells too many. My foot is down, my kids aren't going (without me). I just wonder if feeling this way is wrong?