Hey, I know this was a while ago, but I just wanted see how you were going. I also wanted to say that please don't think you are worthless, a King died for you, wants a relationships with you, and loves you unconditionally. God made you perfect and in his image, and thinks that you are equally as beautiful as the girls you see at school. Don't forget thought that what makes you beautiful is the way you treat others, and the relationship you have with Jesus. Focus on what you have on the inside, and only value Jesus's opinion of you. Let your relationship with him grow, and your light will inspire and lift up others.
With the guy, what he did was very serious, don't underestimate this even if he apologised to you. If he still thinks in his heart that what he did was okay there is a high possibility that a similar occurrence can happen in the future, maybe even worse.
Because you are scared, be sure to tell someone you can trust who is responsible to help you through this and help guide you on what to do. At least tell his parents, they need to have a discussion with him so he knows not to touch another person's body without permission, and not at such a young age. I understand this is scary, but is so, so, so important. You never know, making sure the right actions are taken to prevent this from happening again can save your life and possibly the life of other people in similar positions too.
I hope you are safe and well, and may God bless you with strength, courage, guidance and wisdom.