Thanks for sharing those details. That definitely is a lot to deal with at this emotional time. You mention trouble with relationships with friends as well.. do you have any friend who knows you well and you could talk to for support? They may be able to point out positive pieces of yourself which you are having trouble seeing right now.
Take a deep breath and remember that you are just as valuable as any other human being. You may not believe it, but I believe it.
For your new expensive apartment .. not sure if this is an option where you live, but in some places you can let the manager know that you are looking to move out and they can search for someone else to lease it to. Essentially, you would continue to pay for the apt until they find someone looking to move in. Then the new person takes over. Once the new person is paying rent, management cannot collect rent from you anymore. I have done this before, when I had to move unexpectedly. I ended up paying for only 3 months of rent instead of a year.
That's unfortunate you are recalling classmates laughing at you now. Children (and many adults) are immature, so please try to forget the unsupportive comments from 20+ years ago. Of course, I have memories like that as well.. it is not always easy to push the memories aside.
Sending positive waves your way..