While I feel like I cannot give you decent advice, I can say that you are not "damaged goods" and should never refer to yourself in that way.
Always remember to think before you do something which later you may regret on in court
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You should, honestly hand on heart tell him. If he loves you he'll stay, if he doesn't then he won't. It's not easy, but it will be a breath of fresh air to get it off of your chest. Keeping things from people can only backfire since they're bound to find out sooner or later, whether you tell them or not. And stories can become fictional when they come out of other sources.
You need to tell him anon, if he loves you he'll support you, if not then you deserve better. Good luck.
You need professional counselling. Make an appointment with your GP.
I think counselling would be best, probably with someone from school/college or wherever you're currently studying... but that's only if you feel comfortable to talk to a counsellor about it
You have to understand that your fears are irrational.
I would seek advice from a counsellor or psychologist who has experience in this area.
You should tell him everything and if he does do a runner then he obviously isn't a decent enough guy for you !