Should I Tell My Old School Friend My Facebook Account?

I know this might be a stupid question, but I really need some advice.
So, I have this friend at my old school who asked me if I had a Facebook account so she could add me and I said I did but I don’t remember my password (which was a lie because I wasn’t sure if I should add her and my other friends from my old school)
I know that I should tell them my fb account, and I want to, but I’m scared since I’ve got a lot of my interests, hobbies, what music I listen to, etc. on my profile. I used to be really quiet and unsocial at my old school and I guess I kinda seemed like on of those nerds who didn’t keep up with the latest news, groups, and gossip, etc. but that was untrue. I just didn’t like to show the real me to others, and I really don’t know why. But I’ve been friends with that girl for about 6 years and that was the only side of me that she knew. If I could go back and change myself, I definitely would but unfortunately, I can’t.
But it’s not like I don’t show anyone the real me. I have really good friends who I’ve known for over 10 years because our parents are friends but unfortunately, we never went to the same school although we’re very close. I have them as friends on Facebook.
Now, at my new school I’m starting to be more open, but I still have trouble showing the real me. I have new friends who know what I like and what I’m interested in which is nice but they still don’t fully know the real me like my closest friends do. It’s like I have very different sides of myself that different people see and they think that’s the only side of me.
So my question is, should I tell that friend my Facebook account and show her what my interests are? I’m really not sure since I’ve known her for 6 years but she never knew the real me. I really want to show her though, but it’s really harder than it seems. She doesn’t know that I’m actually a really loud person, that my favourite band is SHINee, that I’m in love with K-pop, which she is also a fan of. If she knew the real me then we could’ve been closer friends but then it’s not only her who I’ll be showing the real me to, it’s also the other people at my old school who never knew the real me and always thought of me as weird etc.
Please give me your opinions. I really need your help. Thanks