Is it wrong to like him?

Okay, I'm very bad at telling stories so I'll try and sum this up as best as I can. A little bit about myself- I'm 18 just graduated high school this May (whoop whoop!) and now I continue to follow God's will for my life as I become a young woman. I, my 16 yr old brother, and my 22 yr old sister grew up in church. My sister is very pretty and has a pretty good handful of guys liking her when she was in high school (private Christian school of about 120 students-all of us go to the same church). When she was close to graduating she became sort of rebellious as all teenagers do. At the time of this rebellion she fell in "love" (lust) with a guy- he was nice but his mind wasn't focused on the right things and my family didn't really approved. At the same time she was liking this guy another guy (he's currently 25, he's so nice and sweet) was crushing/trying to talk to her as well. She was a very shallow person than and was more attracted to the guy who wore better clothes and was on all the latest trends (which was the guy my family disapproved of). Long story short my sister fornicated with that boy and she left church. Fornication is having sex before marriage and in our church and family we abide by that and take it very seriously. It's been 5 years since that. 
When I was younger I was chubby and didn't really care for my appearance all that much. Anyways I had a huge crush on that nice guy who wanted to talk to my sister since I first met him (he's not from my church so I see Him like a handful of times a year). After my sister fornicated, I didn't see much of him until like 3 years ago. We are really good friends now and when we talk to each other it's like nothing else matters and he's the only person I want to be around 😌. He makes me extremely happy and I can't stop smiling whenever I think about him! I know he adores me as a person so that makes it even more awesome when we talk. I'm 18 now so I'm not that little girl he thought was so cute back then...I've grown into a beauty young lady with gorgeous curves and flaws if I do say so myself (it took me a long time to gain self confidence but I finally got it😉). 
My dilemma here is I want to like him...like so bad! I could possibly be falling in love especially every time I spend even a second with him! BUT...my sister... he wants the person he's going to marry in church and have the same mindset as he does. He could have been married a LONG time ago but he's waiting on the right one and he says "if I have to wait another decade it won't matter because I know I'll be happy". Anyways he is not waiting for my sister to come back to church so he can marry her but if she comes back before he's married he would more than likely try and talk to her again. He's also a virgin (as am I) so he wanted a wife who is also pure. He prays she comes back to God as do I but he's not going to wait on her. He sends me mixed signals all the time I'm not for sure if he like likes me or doesn't. I honestly think he's confused himself-sometimes I can tell he really likes me but I feel like he's afraid to admit it... 
If we were to get together I feel like that would be beyond amazing! He's a great guy and I can see my future with him all day everyday. I don't want to feel like I'm betraying my sister if we do end up together and I also don't want to be on edge whenever they're around each other as if he'll cheat on me. My grandmother and him are like so close they hang out whenever their schedules are aligned. He's mentioned to my grandmother that if he didn't like my sister he would have already been tried to talk to me...and that if we were to get together I wouldn't have to worry about him liking my sister because he would be all about me. My sister is steady trying to leave the states to "get out of here" as she puts it but whenever we talk about her marrying anybody she says the only she would ever marry if she stayed here and was in church is HIM. I don't know how to feel about this all...😞 my best friends don't think I should worry about other people but do what makes me happy and if that's being with him than go for it. I wish I knew what HE truly wanted...if he really wants to be with me. My mom said she loves the idea of me and him together but at the same time she doesn't because he and my sister were liking each other for a little bit. Sometimes I feel like why am I holding back on being happy with someone that makes me happy because my sister decided she didn't want the nice guy. She made the mistakes not me...so why do I feel like I'm paying for them😔. I just really like him...a lot. 
Your opinion?
P.S. I told you I don't know how to tell short stories 😝