You used the term “passive agressive” a lot in your post, so I assume you know the opposite of that, which is “assertive”. If you can identify “passive agressive”, you can identify “assertive”. Instead of continually labelling others, label yourself: assertive. Start behaving in an assertive manner. You are paying for the room too. While you owe the others courtesy, you are owed that in turn. It is not selfish or “insane” to expect that.
I would look for another room. There are bound to be some available around campus. Talk to the housing office.
Buy a sleep mask. Insist your RA get involved (if he doesn’t, report him to the housing office). At minimum he should help negotiate a contract: they’re allowed to keep the lights on (you can sleep with a mask), but they should entertain guests in the lounge if you are trying to sleep.
It was probably a mistake to publicly announce you have a diagnosis of depression. It put a target on your back. Unfair? Yes. You aren’t dealing with mature adults though.
Your meal swipes are your business. No need to explain to anyone. Most people I knew in college bought less than 21 meals. It is faster to pour a bowl of cereal in your dorm room than to make time to visit the cafeteria before an early class, and that was in the days before grocery delivery was a thing.
Good luck to you. Hang in there.