What do you think of my sister?

I am pissed off at her. She recently got her first boyfriend. He is white, but only into Asians (we are asian). He broke up with his long distant ex in March and asked my sis out in April. He is still "friends" with his ex who also got her own boyfriend. My sister loves her bf more than me. I really love her but she has no respect for me. My dad doesn't approve of the relationship so my sister has to make me lie about everything. She told him him we were going to library and I thought we really needed to go, but when we got there she asked if I could stay there while she went on a date with her bf. WHAT? I was so mad, I mean you have to use me all the time to get with him?! He is such a creep and I bet my sister is too naive and dumb to notice. I bet she is just a call girl, while he waits for his ex to return to America. Tell me if she is normal or whatever you think about her. My sister and I are really close (only family member) and I get hurt when she uses me just so she could go on a date. Everything she says correlates him. He is 5 years older than her and I hate his guts. I think she deserves someone better.