not a usual "crush on a straight guy" thread

Hello,
I am Greekboy and i just made an account so if this is the wrong section to post my problem please excuse me.
First of all I'd like to talk about me a little bit.I am 17 years old and i have no idea what my sexual orientation is.I've liked girls in the past but boys too.Lately mostly if not wholy boys.I had a platonic relationship with a girl that ended more than a year ago.Since then I discovered that I like this straight guy and guys generally.I haven't come out but i have told two of my best girl friends that i like him.Since then I completely changed.I gained confidence,took care of my self,lost 30 pounds,changed my style and I feel like i redefined myself.After this "makeover" more and more people are suspicious of me being gay.Everyone is and was since I got into junior high I remember being teased or being the spotlight of gossip talk in school.That guy thinks or propably thought about that too.So i think we should talk about him right now.
Let's refer to the guy as J .I'm not gonna describe him as hot,athletic etc because the only thing that matters is that i like him.We've been talking for years but became close friends this year.He is 17 too and has an almost 3year old relationship.And here's the real problem.J's girlfriend is a close friend of mine,we hang out and text every day.I feel so bad that I like him because I'm betraying my friend but I didn't choose to like him it just happened.She's into another guy and is talking about him ALL THE TIME.She says the other guy is the most handsome and sexy guy she has ever met and it's a little pathetic to say that since she is in a relationship.Nevermind
The fact is that I don't know if J is gay/bi straight or whatever he may be.Sometimes i feel like he's flirting with me although he might just be messing with me to see if i'm really gay.I've caught him staring at me many times even checking me out.During a school trip in a foreign country he was inviting me in his room every night.The last night we were in a friend's room and i was sleeping in the same bed with a girl.Around 5am he woke me up and asked me if I wanted to go to his room with him.I said yes but i didn't understand what was going on and i just wanted to sleep somewhere comfortable.His best friend came along but J told him something and he left.When we entered i sat on the bed.He undressed and came right in front of me wearing only his underwear asking me "Are we gonna sleep now?" in a flirty way.I wanted to say no,but i wanted to sleep and what else could we do except for sleeping?Sex?Please I haven't even kissed someone.That day he didn't even talk to me.
J is or at least was constantly touching me near my neck and my head in a soft way almost every time we were on our own or even when no one was staring.(It's boring reading all that,isn't it?We're close I promise)
A couple months ago,one of my bestfriends(that haven't told her about him) and I went to a cafeteria where my ex girlfriend hangs out because my bf thinks i still like her.So we came across J and asked my bf why we came here.She explained to him and J said with a calm voice "Isn't he into guys?" My bf told me exactly how J asked her.She said no so I don't know what he thinks of me now.Lately we hang out a lot,he texts me about anything(LoL,tattoos etc) and he compliments me a lot about my looks and my brains( :roflmao: ).
There are many many many more things that happened between us ie during this school trip he came in my room knowing i was alone wearing his underwear just to ask me which jeans to wear.I'm sorry if all this was boring and exhausting for you to read.There are so many things in my head right now and don't know how to write them properly in here.I just wanted to get any kind of advice on this situation from people like me,who've been through that kind of things.Is he flirting with me or am i just misinterpreting his moves?What am I supposed to do with him?He's breaking up with his girlfriend very often which leads me to the conclusion he might me confused.:help: please :/
Cheers