I posted it got lost due either to the suckiness of my computer or my internet. I can't remember at this point. This kind of crap hapends as siblings, no is a word that some siblings are adverse to and yes siblings can use there children as hostages. All you can do is wait see if it blows over and next time you say yes everything will be back to normal. Accept that as your sister is now this is all she can give and hope she decides to improve herself one day. Just be there unconditionally when you can and never expect anything in return.