First, you need to own up your mistake.
Realize WHY it was bad, HOW it made her feel (even if to you it wouldn't be such a big deal, imagine if you were insecure about your self image, or embarrased about your past, or you were lonely in the past, so friends laughing at things you did lit of boredom feels personal...etc.).
After you realize why and how much bad it is, ask yourself why you did it, to fix it and to avoid doing the same mistake twice.
About your feelings, you shouldn't tell her about "how bad you feel" or "I'm really hurt", because 1) you did this 2) you're making this about yourself, when you shouldn't
You may try to send her a text through telegram, or get a mutual friend, to do you the favour of sending a message to her (obviously, you will need to repay that friend). Something like:
"I'm sorry. You are a great friend to me, and I did not act like a friend should have. It's completely understandable if you don't want to continue being my friend. I messed up.
At the time, I didn't realize, (don't try to put excuses, be careful if you want to explain why, you shouldn't defend your actions) but after seeing your reaction and putting more thought into it, I now understand how wrong I was. I'll work on that so it never happens again, regardless of your decision.
I hope you let me make amends, so that we can continue as we were before"
After that, it's her decision. If she passes near you, don't try to make a conversation, just "good morning/afternoon/hi" and if she ignores you, you got your answer. She may change her mind, but it's not up to you.