So this is my first time posting here, or on any forum, but I have nowhere else to turn for advice. I'm sorry if I make this too long or something, it's a long complicated situation.
I am a junior in high school and am dual enrolled in my local community college - by the end of my senior year I will graduate with an associates degree. I have grown up around people older than me, and it reflects in my bearing - I am not wired to think or act like a 17 year old, many people I meet think I'm in my early 20's. All in all I am very mature and have high hopes for my future.
The one area of my life that has continuously failed is relationships - I have NEVER had one work out, from middle school to now (approx. 6 relationships). Of those, the most serious was with a girl I dated for just over a year, until she slept with another guy at a party and effectively ended the relationship. That was in October 2014. After that relationship, I developed severe trust issues and a fear of commitment, along with my anxiety (which I know I have) and this fear I have of losing everyone I'm close to (stems from a lot of failed relationships and deaths over the course of my life). I went from October 2014 to December 2015 without even attempting to talk to a girl, I was that scarred. Then things changed.
I work at a grocery store, and this new girl started in December. For the sake of anonymity I'll change her name to Katie. Her father had started working there about 3 months beforehand, and I had trained him and have to this day a great working relationship with him. Katie and I immediately hit it off, from pretty much day 1 we would flirt all the time, and after a few days I got her number. We started talking all the time, and developed a very close friendship. Neither of us asked how old the other was - I figured she was 19, and come to find out she thought I was 19. Turns out Katie is 23, turning 24 in June. By the time we found out, we were very close, and I had started developing feelings for her in a more romantic way.
I took a chance and mentioned her to my dad, being honest about the age difference but hoping that he wouldn't mind me wanting to get to know her better. He was noncommittal during the conversation, later that night my parents sat me down and talked to me about Katie (he had told my mom). Instead of being cool about it, they freaked out, and told me I would NEVER be allowed to pursue anything with her, that if I got caught TEXTING her I would lose my phone, and that I had no business liking someone 6.5 years older than me. This really pissed me off and I ignored them based on the strength of my feelings - Katie had broken down walls I'd spent over a year building up.
From mid December through January, Katie and I continued to talk every day for the vast majority of the day. We would take lunches together at work, one time I was able to go spend a few hours with her, and we'd visit each other at work all the time. Our relationship got stronger and stronger, we started the first steps of intimacy (hugging, hand holding, etc., haven't kissed). Finally I told her exactly how I feel, and what I wanted for us. She said she felt like we could work out, but she didn't want anything serious at the time because she too has a fear of opening up to others due to an abusive ex of 3 years. She says one day she wants to be with me in a romantic way, but that she just needs a little longer to open up herself.
On February 1st, I came home from work and instantly was harassed by my parents. I had to turn over my phone and then my mom produced a stack of phone records showing all my text messages for the month of January, and she proceeded to ream me for talking to Katie when she told me not to. She told me that she barely kept herself from going to my place of work and harassing Katie, and from calling the cops. My parents were about to make me quit my job over this. They told me if I get caught talking to her again they WILL call the police and get her charged as a sex offender (which she is NOT, and her and I have done NOTHING). I was very upset, went days without talking to Katie, then I caved in and downloaded a messaging app to talk to her with, to avoid sms logging. This was about 2 weeks ago now.
Last night I came home from work pretty late, and my parents jumped down my throat about it and then accused me of still talking to Katie and saying they think I was with her instead of being stuck at work late. Then my mom told me she had TRACKED KATIE DOWN ON FACEBOOK AND READ EVERY POST, and my mom said, word for word, "the love of your life is white trash". She also said she wanted to "snatch that ***** up by her hair for being interested in me", and tried to tell me that Katie had been involved in an affair of 3 years with a married man who had 2 kids. NONE OF THIS IS TRUE, she is not "trashy", she had NO affair (she thinks that type of thing is wrong considering what her ex did to her), and my parents are being so horrible to me about her! They told me for a final time that I am to have nothing to do with her anymore.
I have told Katie all of this and she is upset by it, she doesn't understand how my parents can be so judgemental and cruel to me about this, considering at this point we are just very close friends (though we want something more). It is also worth mentioning that I turn 18 in October, and my parent said even then I will be forbidden from anything to do with this girl outside of work.
I am starting to love Katie. She makes me feel the happiest I have ever felt. She is sweet and caring and funny and the best person I have the privilege to know. I want nothing more than to devote myself to her, the thought of losing her absolutely terrifies me, and neither her nor I know what to do now. My parents have no problem ruining my life over this, and they'd go so far as ruining Katie's to do it. I am starting to hate them for the way they're being to me, judging this girl I've come to care about so much when they have never even met her.
I don't know what to do, I am so scared I'll lose Katie, but I'm scared of what my parents might do if I keep talking to her... I've never let myself get so attached to someone before, not even the girl I dated for a year (who I could never bring myself to tell "I love you"). When I'm with Katie I feel RIGHT, I feel like the luckiest guy in the world. I would be absolutely devastated and probably scarred for life if I lost her because of my asshole parents... what do I do? How do I live with this scenario I'm in?

Thank you for your time, sorry for the long read.
- Brandon