What do I do to avoid the friendzone but still keep her connected/interested?

So here’s the scene. I like a girl.
Problem 1 – I’m friendzoned.
Problem 2 – She has a boyfriend.
Problem 3 – I never wanna quit.

People back off from answering me the solution after reading problems 1 & 2. I know most of you may think it’s impossible and better to go looking for someone else. But then arises problem 3.
So here’s the scene. There’s a girl. She’s a friend of mine since past 2 years. First, I considered her as “just a friend” and even she didn’t show any interest going in the “love” direction, so we became the best of friends- me never thinking about doing things that would turn her off ‘cause she was like a girl best friend. We laughed, played without ever having even a tiny thought like “Eww.. what he’d/she’d think about me if I do this?”.
So here’s a mistake already I made – got myself deep into the friendzone, with such a long time plan.
We both used to go to each others house, have fun & eat together (with our big friends group). We are in a group of friends and always hang out together. There were times when there would be only me and her but most of the time at least one more person used to be there.
I know every one in her family very nicely. Many a times even if she wasn’t there, I used to spend time with her family as if it was my family. Everyone knows me very well. Every one believes that I come to meet her and talk to her almost 90% of the times about studies and academics.
Then came this fine day when something happened out of nowhere and I felt upset when I didn’t meet her for some days. It was a very unusual feeling. She ran on my mind all day. This was weird. It never happened for any other girl, not even for thism girl before this day. Slowly I understood I was attracted (in a good way). I actually never knew how it happened but it just happened. I was loving her. I couldn’t think my future without her. I took extra care of her and did all that stuff that I could do for her because it just made me feel good.
She is 3 years younger than me. So while I was going through this, she was enjoying my friendship just like the guy best friend relation. She made me her best friend (threw me at the rock bottom of the friendzone well).
I was dumb at that time to not tell her that I loved her (my mistake). I was waiting for the “right time” which actually never comes (I’ve read a lot about love & relationships and pretty much understand things…now).
I was freakin’ afraid to speak ‘cause I knew if all didn’t go right, she’d be hurt and wouldn’t speak to me and because I know her very well, I also knew it was damn difficult to convince her for anything. Once she’d break the friendship or something, it would directly be God to fix the broken string without a knot in between.
I gave her hints that I was in love with someone (my mistake of never speaking clearly and directly, always making the other person think by giving hints which was annoying). She desperately asked me everyday who was that girl. It wasn’t a jealous feeling, she was just happy for me. There came this day when so many hints pointed her. She got to know. I told her she was the girl. I told her that I loved her. She was shocked exactly like I had thought.
There were some more friends whom I told about this (again my mistake). A friend of her told me that she had a boyfriend and she never told anyone about this ‘cause things spread very fast. Only that friend was the one who knew about it.
This is because her family is very strict. They’d ruin her life if they’d have come to know about her boyfriend.
I used to see her boyfriend sometimes when I used to go out and he always smiled at me. I knew she would have told everything about me to him.
One day, I spoke to him. We became friends. Not always, but sometimes he used to ask about what did she like to eat, etc. and I used to tell him some things (not all). He had an average-good body language, good looks and was a fine guy.
There came a time when the girl and I became friends (not besties) again and we both knew about her boyfriend. She never spoke to me about him until I came up with such a topic. I tried to find out some things and got to know that her boyfriend was actually very bad at studies and lacked any kind of talent or something. He wasn’t even actually studying, he was doing some kinda useless course. He was that type of a guy who just wanted a girl to lovely chat with and hang out, have fun the every other day. No talent, nothing productive in him.
The girl whom I like didn’t bother about these things! I thought there had to be some kind of fishy thing ‘cause how could she just neglect every bit of it?! I found the answer. Her friends had boyfriends and she felt very alone. Her friends would make her feel that she didn’t have something which every girl wants and has and had pity on her. This happened for a long time until she met this guy who was a friend of a guy who was a boyfriend of this girl’s close friend.
When they both got into a relationship, the girl’s friends spoke to her about him and all that stuff that a girl would love to speak about. She thought if she had achieved something and it was good. She just felt great. She started loving all that. She started loving him. And her boyfriend? He started making her fall in love with all ways he could.
The present scene : I still go to her house every day, meet everyone and even her. We still speak like we’re just friends. She started reducing the number of times she used to come to my house from the day when I told her that I loved her. Now, she doesn’t come over to my place. Apparently, never. If there was some important work of her brother or someone else, she’d just come to talk but never come inside my house. It’s like she has no interest. Even if I don’t go to her house for weeks, she’ll never bother. When I go to her house, she just talks about studies and all and if I could teach her something. Nothing more. Just a formal conversation regarding academics or related work. I still have feelings for her.
She can’t like roam around with her boyfriend at all and meets him maybe once or twice a week after college or I don’t know at what time and what place. It’s planned like that so her family doesn’t come to know or suspect someone.
One more thing- Facebook. She chats with him every day for an hour or two (and the time is also fixed sometimes). She never chats or sends a message until I start and it doesn’t go long no matter what I talk about. She doesn’t just stop replying, she just tries to reach the end (not too fast like in just one message answering me my question showing no interest like a rude one, but the conversation doesn’t take long to move to the end). And that guy- he chats for hours and tells her all sorts of things that will keep her attracted and connected always.

I know I’ve done a lot (maybe more than a lot) of stupid mistakes and I may never be able to make up for it. I’m not even asking for a straight way to success or anything.

It’s just that, if there’s even a little bit of faith that remains, I don’t wanna go friendzoned again. I’ve read many articles and all on the internet that I shouldn’t go behind, say “no” when she asks for something, deny requests from her, be unavailable, etc. to seep out of the friendzone. But if I do this, it’d be like going far from her, ‘cause I know she won’t be interested to look for me until and unless there’s some “work” that she has for me. On the other side I’ve read I should make her feel positive in my presence, make her laugh, tease her a bit, help her, be attentive, etc. But if I do this, she’ll again walk on the friend road and I’ll be slowly drowning in the friendzone well.

I’m not sure if something’s gonna ever happen. But I don’t wanna quit and just stop trying from my side. What I want is to remove from her mind that she has to always pick the friend road when she talks to me and being concerned when I’m unavailable.

Suggestions?

If your answer is like I should stop wasting my time and focus on my career, etc., I’m actually not wasting any time, I’m average in academics and do lots of activities I love.