she's a ***** but I'd say you have no rights Im afraid
Butter up your sister-in-law and she'll come around.
i don't think you have any legal rights. sometimes it's hard to get along with in-laws, but in this case, if you want to see your nephews again, you'll have to talk it out with your sis-in-law. find out her reasons for banning you, listen to her, don't argue, apologize when necessary, and agree to whatever terms she outlines. she's in charge so you'll have to follow her rules. let her know you'll honor her wishes, even if it means supervised visits. it hurts too much not to get along with family, you'll just have to drop your pride and play really really nice. i hope this turns out well for you!
You have no rights. I suggest you make your own babies.