It's valid to feel scared about this new experience and really good that you can express your fears to other people.
My first thought as I'm reading this, though, is that your size is thoroughly unremarkable. It may not be where you want to it be, and you're doing great taking control of that and changing your life through having gastric bypass. But at your height and weight, surrounded by adults as you will be in college (and not middle school bullies), your weight simply isn't going to be a thing people notice about you all that much. I had my surgery when I was just slightly under where you are now, and I honestly had a friend (who is average weight/skinny) express total shock at my choice because she thought I was "only a little overweight" (while I thought I looked like a Macy's Thanksgiving parade balloon on two legs).
Other people do not see us the way we see ourselves.
In your mind, you seem to see yourself as worthy of being judged poorly and disliked for your appearance. I would ask, is this how you look at other people? Do you only befriend skinny people? Do you think fat people are terrible? Because if you do, that's a serious personality flaw that I would be way more concerned about fixing than my weight. And if you don't...neither do most people. Also, if they do? See my point about it being a serious personality flaw. Don't give that kind of person power over you. Your existence, exactly the way you are at any point in time, is not the problem. A person who is judging you for existing is demonstrating that their opinion is not worth considering.
Most people don't notice weight first, unless maybe when someone is truly remarkable in size. Most people remember a person's confidence, humor, and overall disposition. They might remember a beautiful smile or a charming laugh, or maybe how you wore your hair or a colorful scarf. They want to be friends because they feel a connection to your personality, not because you have the "correct" size tag in your jeans. Again, if this is not the case, ask yourself why this is someone you want to concern yourself with.
The person you want to be is not just a "skinny" person. At least, I really hope not. I would encourage you to make a list of 10 qualities right now that you want people around you to see and remember about you, and none of them can be about your weight or similar societal measure of physical attractiveness. Focus on that list. Do you want people to see you as smart? Kind? Funny? You can be all of those things today. You probably are all those things right now, if you let yourself believe that it's true. You don't have to lose a single ounce to make that happen. Do you want to be someone who takes care of your health? You're already doing it. Who eats right? Who exercises? You're that person now.
Focus on the things you have control over. You don't get to choose your weight. None of us do. But you can make food and activity choices every day that promote a lower weight. You can't make a specific person or group like you. But you can be the kind of person many people will like.
I wish you the very best of luck. I really wish I had known 30 years ago how absolutely, perfectly fine I was without changing anything, and how little other people's judgement actually mattered. It would have made so many things so much easier.