I think it’s a smart decision. I also think we have a vision that college should be “the best 4 years of our life” which doesn’t always hold true for most. It will be just a blip on the big picture in life and judging from your grades and professors…you will go on to be successful. AND Debt free!
Have a great time in London!!!
It won’t be easy, grind it out, one step at a time and don’t weaken. And no “snapping” allowed. 
Best of luck.
This is a great time to get in touch with your inner nerd. College is also about academics.
I personally think you’re resilient enough and tough enough and as I mentioned, a lot of it is framing. Remember that if people are high schoolish in their treatment of you, it’s them, not you. Pity them for their human failings and focus on your goals. Examine yourself and what is meaningful to you and do right as you can. Tue recht und scheue niemand.
College has been 100 percent academic for me. But there’s also a part of me that’s human that wants more than just academics.
Everyone here is on your side.
Studying abroad can be a life changing experience.
My professors encouraged me to get out and to go see London and also, gratefully, they also encouraged me to not do anything academically rigorious over there and to take a break and study whatever seems fun, interesting, and exciting. That’s honestly the one thing that’s giving me hope
See if you can join some local groups/volunteer when you are in London. I lived there 4 times for extended periods, and besides my menial jobs, I also went to CND meetings (it was the 80’s) and volunteered with Passports For Pets, which worked to abolish Britain’s 6 month quarantine law.
They are a nation of animal lovers, if you are too you can find like minded groups. Or join the Victorian Society, or the Georgian society. Of course there are tons of LGBTQ groups too. So many things!!!
I echo what @Publisher said: we are all pulling for you! Anytime you need a virtual hug, or pat on the back, come back to this thread (or start a new one)!
sounds like you have great professors
As an aspect to consider as you reenter your college experience, the Princeton Review (2020 edition) includes a “SURVEY SAYS . . .” heading under which a line might appear depending on student responses to the question “Overall, how happy are you?” For USC, nothing appears. For Hamilton and Williams, the guide reports that “Students are happy.” As a further indication of student satisfaction and success, Hamilton, Williams and Middlebury all register much higher 4-year graduation rates than that for USC: https://www.usnews.com/best-colleges/rankings/highest-grad-rate.
Sounds like you have remarkable support at your LAC which would be hard to replicate at USC. Is it possible you are homesick? That would be understandable.
I really hope that COVID restrictions loosening, improves your social and emotional life.
Use all the resources that you can. Try to find some things to do off campus. Not sure if you are taking medication but that is always a possibility.
The London experience will be great. You are intelligent and articulate and I really hope you can find your people at your LAC.
I can tell you, that other people are happy because of how homogenous they are to the school’s environment. Northerners, wealthy individuals, white, etc. I am very unhappy with where I am at.
I thought it was homesickness but I don’t think about my parents or home that often. I think of my inability to socialize with people before and during COVID. Most of the people I’ve interacted with at my school have little to no interest in me or the hobbies I enjoy. There’s nothing off campus, and I mean absolutely nothing. I am not going to do meds. I’ve already done that and I almost snapped. My last resort is to go overseas.
I’d strongly encourage you to investigate if you can start your abroad study this Fall. Many if not all UK schools start in October. You have time to see if you can enroll and obtain a student visa. London is amazing!
Then you’d have just 7 months left of school to deal with when you return to the US. 
This tells me that you’re strong, both body and spirit. 
The following suggestion is something that I truly believe in myself, but I know it’s not a cure alone. Have you tried exercising regularly? To borrow a line from a old movie: “Exercise gives you endorphins. Endorphins make you happy.”
Similar reactions by URM students of color has gotten some attention at Williams College in recent years. Yours is certainly not a unique reaction.
Unfortunately, I’ve tried looking into that but deadlines for declaring a leave off campus are already over. 
I also need to take certain classes available fall 2021 to complete my double major on time. I just hope the months I have left at my LAC, I could just focus on finishing my senior theses and get the hell out of there forever.
I just go to the pool every now and then to swim
OP: You have done everything that you can. Now that you have made your decision, you need to focus on positives.
Uncomfortable as the environment is & may continue to be, all you can control are your activities & your thoughts.
Positives include: Quality of education, cost of attendance, study abroad, caring faculty & therapist. Also, I think that it is a positive that you are thriving academically under stressful conditions / environment. Plus, you have unanimous support & admiration from all CC contributors as far as I can assess.
Focus on your health, your work, and your upcoming study abroad.
You are a strong person.
Positives.
P.S. If appropriate, try complimenting another individual or organization. Can be done in person or via a letter to the student newspaper. For example: After you return from studying abroad, consider writing a letter / article in the student newspaper about your experience in London. Never be afraid about complimenting another; be cautious & careful with criticism.
I think things may be different if COVID restrictions remain loosened.
ps it is not a weakness to take meds; it can be lifesaving for some and takes wisdom and strength. I don’t know the OP so this comment is not geared to the OP’s situation specifically