I have started a new family and it has affected everything. My kids all get along great, it is just the Ex continuing to make our live miserable. I feel that if I made this decision to reliquish rights it would help the situation with my family, but on the other hand not fair to my girls... If I made this decision and continued to pay child support the question would be would she continue to make our live miserable? I asked my Father for some advice, and he said to do what I need to do. He also told me my child support would go up.. Is that true? He also said that they as grandparents have rights...
No, as grandparents they do NOT have any inherent rights. They might have statutory standing to sue for visitation rights, but even that is not guaranteed.
You honestly need to tell us what rights it is that you think that you are giving up?
You can give up your visitation and custody rights and simply pay child support and have nothing to do with your children. You don't have to go to court or anything else to do that.
Or, you could terminate your parental rights (assuming that mom is married and her husband is willing to adopt the children and take over the legal responsibilities towards the children). In that case, you would not owe child support any longer, but both mom and her husband would have to agree to that course of action.
I can think of absolutely no way to guarantee however, that mom won't continue to make your life "miserable", because you haven't explained what she is doing now to make your life miserable.