4.5 year old hates me!

Hey everyone.I'm not a biological parent but I am here today badly needing advice.I'm 22 years old and have a 4.5 year old sister who I care for part time due to my parents working. I'm currently pregnant with my first baby so I'm out of work and I stepped in to care for my sister.I've raised her part time since I was around 17 so she knows me very well as one of her carers. I moved out when I was 20 due to my parents basically pushing me out (Despite all of the child care help I've given them over the years) However, I still maintained regular contact with my sister - seeing her perhaps 5 times a week.About 6 months ago she developed a total dislike towards me. It had nothing to do with me getting pregnant as this was wayyyy before that. She started off by refusing to hug me or give me a kiss when she was saying goodbye to me. I thought this was just a phase, but it's gotten worse.Whenever she sees me now (If I'm visiting my parents) She will scream at the top of her lungs and say out loud "Oh no, it's my sister." - To everyone else this is hilarious, but to me it's incredibly hurtful when I dedicated a large part of my young adult life to caring for her.She won't come anywhere near me when our parents are in the room, she will scream if I even sit on the floor near her when she is playing. She doesn't do this with anyone else. Whenever my dad is in the room she will shout 'Help me, Daddy!' if I even sit near her. My dad does nothing to stop this, he actually sides with her (SHES 4!!!!) and tells me to leave her alone even though I'm doing nothing wrong.I have no doubt the reactions of my parents are what is causing this to go on and get worse. She only plays up with me and says she doesn't like me when our parents are in the room - they simply laugh at her, as truth be told I don't think they like me much either. I had a very bad upbringing where they constantly excluded me - but that's another story.The only time that she's sweet with me is when we're alone or I'm doing something she wants to do. For example if I offer to take her to the park she's my best friend. Or if one of my parents tells her to get dressed she all of a sudden wants a cuddle and kiss from me. I feel used by a 4.5 year old and it's really getting me down. I know that sounds pathetic but I just love this kid so much and she seems to hate me.On a few occasions when I've been alone with her it seems as though she's mimicking things she has heard our parents say about me. She has previously called me lazy, said that I'm dirty and even pointed at my stomach on one occasion and said 'poor baby' - Where would a 4 year old get this information from? My disgusting parents that's where. Along with this, she has outright told my partner of 3 years that he has 'no work ethic' (AGAIN SHES 4!!!!!) even though he works 50 hours a week to provide for us. He also provides for her aswell when she's staying over.Out of anger I've confronted both of my parents and neither of them are bothered by how angry it makes me. I've told them they're making their own daughter dislike me and my partner. My dad will just shrug it off, and my mom claims she doesn't know anything about it. She says 'kids will be kids' and 'kids say the silliest things' KIDS DONT SPEAK ABOUT WORK ETHIC!It's so hurtful. I know I've said this before but I dedicated my final teenage years to raising her, I didn't have much of a social life whereas my parents did. They were always out seeing friends whilst I was stuck inside with a baby that now hates me.I honestly don't know what to do. I love her so much, I see her as my own child and I'm scared to lose her. I've never once treated her badly in her short little life. I've never hit her or laid a single finger on her, so when she screams HELP ME I just feel dreadful. I could cry.My relationship with our parents is incredibly bad, and as I said above it always has been. It was borderline abusive growing up and into adulthood they've always made it clear I'm a disappointment and not truly welcome in their house. The love I have for my sister just keeps dragging me back though.Please offer me advice.Thank you.EDIT: I'd like to add, I have another sibling. A brother who is 18 years old and moved away from home when he was 17. He never really comes home anymore, and I'm sure you guys can imagine why. My little sister is very loving towards him and adores it when he visits home. I think it's just me who she dislikes. Growing up my parents weren't awful to him the way they were me, when he moved out my mom cried and said she wanted him back. via /r/Parenting http://ift.tt/2ttTszU