[winter444]

I really, really feel for you in this situation.
As others have said, I'd write to your dad and explain to him exactly how you feel.
At first reading about your sister I thought she was acting like a spoilt child but as I read more her behavior has been just plain nasty and should not have been allowed to go on. People seem to be letting her do this over and over.
I would definately stay in contact with your dad but your sister has to be shown she cannot, and will not, treat you the way she has been doing. honestly, I would not contact her, no cards, gifts, nothing. I think to keep sending her stuff kind of tells her she has control over you.

See what happens when you don't contact her, my god you have been so kind to her but it really sounds like she has a LOT of problems, is very abusive and this is just not healthy for you, you have to think about yourself. No one asks for their family and I truly feel that if any of them are just making our lives miserable, we have to stop it.

I totally understand when you say you don't want her to get away with this, it is infuriating to say the least, I had the same problem with one of my 1/2 siblings concerning my bmom, this particular sibling would not let us have any privacy and commented on everything I said, honestly I was so ill from it and now there's no contact with bmom. Honestly though I would stop contact with your sister and write to your dad or talk to him, he needs to stop enabling her and see what's been going on. You deserve to have a relationship with your dad, it makes me so angry when this kind of thing goes on.
All you can do is say how you feel and you can't take this abuse, you are doing nothing wrong. Let the other bfamily members know how you feel too, seems that they already know from what I've read. Everyone needs to stop enabling this girl but it may never happen. Sorry but it just makes me want to throttle some people!!!!
Take your sister out of the picture for right now, who knows what will happen in the future, she may grow up....if not, sister or no sister I would not want to be around her anyway. Also, by you being strong where she is concerned you are showing your dad and the others you don't tolerate this behavior.
When someone is acting like this, it can really make us physically and mentally ill, it's torture.
You deserve peace and happiness x x