I've nc'd for this one.
There's a massive backstory to this but the jist of it is my dm left my df after a couple of decades of marriage - he rebounded and married the first woman he could find, who turned out to be a spiteful, insecure woman who went to great lengths to cut me and my sibling out of my dad's life.
He left her after a year of marriage and made the mistake of kindly telling me everything bad she had ever said or tried to do with us and then after playing the field for a couple of months and sleeping at my grandparents he realised something was better than nothing and went back to her. When I called him out on going back to a woman that he knew openly despised his kids, he flat out refused to believe he'd said anything and then refused to talk to me or see my then 1yo dc for an entire year.
After a few attempts on my part to sort the issue out we did start talking again. Fast forward a couple of years and we live 3 miles away from each other and I have another DC. He's turned out to be an appalling grandfather, will only see my DC's if he really has nothing else to do (mainly golf). They have recently adopted a child exactly the same age as my youngest and I have suggested a number of times that we get them together as they are now technically my sibling and I know very little of them and I thought it would be nice for my DC's to get to know them. But no, his wife has made it quite clear that she doesn't like me and doesn't want us to have anything to do with the child.
It's probably worth adding that when I was contacted by the social worker regarding the adoption that they'd lied about a lot of things - namely the level of contact they have with me and my DC's. They had said they saw us weekly, we had dinner there, went on days out etc, which was obviously lies as she's only seen my DC2 twice since birth (now well over 2). Obviously in the course of speaking to the SW this came out and the SW was 'very concerned' but it went through anyway. My dad has found out about the conversation and even though he hasn't challenged me on it, knowing he can't expect me to lie for him, he said he 'wasn't happy' with me not towing the line.
So, recently I asked my dad to babysit (third time in 6 years), he said yes and then pulled out the day he was meant to babysit because he has a sore throat - he's ill EVERY week so this is nothing new. I came to the conclusion that there was absolutely NO point in trying to continue the relationship, he will never consider me and my DC's a priority in his life, he doesn't call or visit for a cup of tea to see the DC's, he's only ever taken my eldest out once in 6 years. I've spoken to him umpteen times about trying do more as a family and he agrees but nothing ever happens and I'm pretty sick of being made to feel grateful for the scraps of time he gives up - I am constantly being hurt by his lack of interest in anything to do with us. If my youngest does something, his adopted child did it 6 months before and with bells and whistles on. I've told him it's not a competition and I'm just trying to bring him up to speed but he's never just listening - always just waiting for his turn to speak. I had to tell him SEVEN times we were going on holiday recently and each time it was like I'd never mentioned it - I had to go through the where, when, how long thing each time.
After the babysitting incident I emailed him and said how I felt and I thought it was best we stopped contacting each other. He never replied or picked the phone up to talk about it. The problem is that my eldest absolutely adores him - has talked non stop lately about when he'll be over to see them next etc. I've deflected the conversation because I simply don't know what to say.
Have I done the right thing? He's not inherently a bad person, just very very selfish and lives in perpetual fear of being on his own so will not rock the boat in terms of crossing his wife - if she says he has to go shopping instead of seeing us, then so be it. These are obviously his choices to make but I've lowered my expectations of him and even those aren't being met, he just doesn't care that much, I don't think 
. How do I address it with my eldest? Should I allow him contact with them, but then how will that work with my youngest (who'd never have any relationship with him)?