<human>: Long story short, my ex bf cheated on me with his 11 year old niece. It truly disgusts me. 

I now have a new bf, with whom I've been with for 2 and a half years. His little sister [11] practically worships him and is constantly all over him and wanting his attention. I know part of this is because that is how kids are, but I can't help but feel threatened by it. I barely want to spend any time with her, and I get truly nervous thinking of her spending time with him. I trust him 100% and know that he would never ever ever do the same thing to me as my ex. But I want to stop feeling this way towards her but I have been trying for a long time and I can't. 

I don't know how to even begin not thinking the way I do about it, because shes constantly putting her butt in his line of site or just all over wanting all sorts of hugs and such. Maybe I just look at this differently because of what I've been through but it truly bothers me. Can someone give me some insight on how to stop feeling this way? I've spoken to my boyfriend about it and he's reassured me he'd never do such a thing, but I just really don't wanna feel this way towards her forever..

Give me a shortened version of the text
<bot>: My ex bf cheated on me with his niece, how do I continue forward with my SO's little sister who is constantly all over him?