I am terribly devestated right now. I am angry at myself, my dad and my grandparents. The thing is my grandparents sold my dog, who is more like a part of the family than a dog to me. I was happy to see him when I returned home from school each weekend. But now I don't really have a reason to be happy. I feel so empty inside and what's the worst they didn't even say sorry or anything like that to me. They even said I shouldn't complain it barked a lot anyway. I am soo angry at them and I am asking you right now what is the right soultion to my problem. No I don't want another dog! I want to know how to forgive them beacause it is hard and this is not the first time something like this happened, my mother left because of my grandparents and I know how she felt now.

First, cool off. Shut yourself in your room, ignore their existence, take a walk, do whatever and take as much time as you need to (so long as you're not harming yourself or others).

Then, talk to them. Make a list of questions, write a script, find the truth and reason behind their decision.

And if in the end you conclude that they themselves (as a person) are absolutely terrible, then you do have the option of cutting them off (which is extreme and difficult to do since they are family).

Note: The deed may be terrible but if you are able to understand their reasoning then forgiving them would be

Is it possible to get back the dog? I'm mean, if you explain the situation to the new owner, he will at least let you see your dog, if he's not a jerk...
I find that your dad and grandparents are terrible people, a dog isn't just an object you can sell like that...

My best friend had a similar expirience. Her grandparents put her second guniea pig to sleep. The first one died of cancer so it was extra hard for her. She ignores them, but I wouldn't ignore them forever. I'd ignore them for like 2 months and then do the things Thorns said. The longer you wait, the worse it is for your grandpa and dad. Trust me. (sorry if there are any gramatical errors)