How do I tell her?

Hey I (27M) am getting engaged with this girl... Obviously arranged marriage. We've been talking for over 3 months now. I had my past that I wanna share with her and only if she accepts that then only I want to get engaged to her.

FYI, when I was in school I never even interacted with girls even though it was a co-ed. After 10th a girl took admission in not only my school but in the same class as me. I fell in love at first sight... I just wanted to be with her, but due to no skill of female interaction I couldn't even break the ice with her. But then suddenly she approached me herself and then we first started talking. It was only me she used to talk to the most. We became friends then best friends and she then asked me if I have a crush on someone I just didn't wanna say that It was her (for context I never LIE... I mean never ever). So I just dodged her question for which she came more aggressively to which I had to admit defeat and told her everything after our final exam.

What happened next broke my heart like anything. She told me on my face that I don't look good so she won't go out with me to which I asked that then why even approached me to be her friend. She replied with "so you wouldn't try on me". Dude how messed up are you up there. She rejected me for looks even though I get compliments around for it. I was so heartbroken that I took it on my ego and just went on a relationship streak... Yep you read it right I exactly got into 53 Relationships after that even with my bad attitude and all.

If you're thinking why stop at 53 then I must tell you that I again fell in love even harder with this girl named potato for instance. Potato and I started going out she also loved me. We were like the best couple around.

When I thought everything was going great in life, I jinxed myself. I developed this clot in my brain due to some past injury and doctors told me to not take stress as it would have severe consequences or even death. I didn't want to break this news to her and you already know that I don't lie so I took help from her friend to make her break up with me so that she doesn't have to suffer if something goes awry. But that devilish friend not only told her about my condition but also told potato that I was hitting on her even though I'm in a relationship with potato. She added that I was lying cause this thing can't be true. Then just misunderstandings started piling up. I told her everything myself this time, but she didn't believe me. I had to send my reports to her, but potato denied them calling it a fake and all. Remember dr. Told me to stay away from stress but I was getting more and more of it.

After listening to everything and seeing every report she still left me which I did not expect at all even in my wildest dreams. I don't know what her friend filled her ears with, but she wouldn't believe me at all.

Yes, I wanted to break up without telling her about anything so that she didn't have to suffer because of me but now she did know everything and still chose to leave me, which made me suffer instead. What acted as a salt to the wound was she getting into a relationship with another guy the very next day.

I was supposed to not take stress but I hope you understand what I would have been through those days. Only I know how I survived it and guys I'm fine now and only have to suffer some minor headaches now and then but everything else is fine. I have never ever tried to be in a relationship after that. So that's why it stopped at 53.

So this is what I want to tell my fiance to be. How should I go about it? I can't lie coz I've never lied. I am only willing to start our life with she accepting my past. I don't wanna ruin her life by telling her after the engagement or marriage. I'd rather stay single for life than sabotage someone else's dreams.

So please help me!!!