mjhjmtu

I'm an immigrant, I moved a year ago to live in the UK. I also struggle with a combination of mental health disorders: BPD, depression and dissociation.

Today I had my first job interview, and it was disaster! I was 20 minutes late because it was a long journey by bus, and then I needed to walk. However, I apologised and they let me in.
After I began filling out the forms, I started have negative thoughts. When the interviewer started the interview, I moved towards his colleague's table and said:

I'm sorry. I give up the application for the position, I didn't fill
so many details.

Then the interviewer asked me "You're not interested any more?". I said I'm interested. "Do you struggle with English? " he asked. "Yes" I replied.

But it wasn't the true reason. It was a panic attack. I stopped medication months ago and was depressed over the last few weeks.

I need your help to write an apology letter for the mess I did.

Don't worry about writing an apology letter, try and move forward onto other opportunities instead.

As a priority, you need to work with your doctor on your health/medication issues and get your health and well-being resolved. When you've done that, you'll have a better platform from which to look for work.

Unless you get your health sorted out, you're likely to run into this same issue again and again and again.

As @snow indicated, a letter of apology isn't absolutely necessary here. That said, it would be a nice gesture and may make you feel more at ease with yourself. If that's the case, such a letter could be very short and simple:

Dear Interviewer:

Thank you for meeting with me on the date to discuss the employment opportunity. Unfortunately, I could not complete the process. I apologize for that. It is my hope that you have good fortune in filling the position.

Sincerely,

Your name

You'll want to change the italicized parts appropriately. Also, tailoring this to better fit your own writing style and the particulars of the situation would be good.

The above is assuming you're not going to pursue this job. There is no guarantee that they would re-consider hiring you, but if you want to try, a modified approach would be in order. In such a case, it might look more like:

Dear Interviewer:

Thank you for meeting with me on the date to discuss the employment opportunity. Unfortunately, I experienced a panic attack and thus could not complete the process. I apologize for that.

If the position is still available, I am still interested. If you would be so kind as to re-consider hiring me, I would like to come in for another interview. Would you be available on (dates when you're available)?

Sincerely,

Your name

To be honest, the odds may not be very good for you to be re-considered, so please don't get your hopes up too much. Of course, if they do call you in, you'll need to be able to complete the process.

As @snow said, taking care of yourself is necessary here, as you'll need to be able to function at work once you get a job (this one or another), and - more importantly - for your own well-being.

Do not bother with the letter.

Concentrate on your health.

Get that fixed and take the medication

My advice is to not send a letter to the company. Generally, people way overestimate the amount of thought that's given to an applicant that's not given the job. One way of looking at it is: if you went to a car dealership, and looked at 8 cars... how often do you think about the 3rd car you looked at and decided you didn't want? Probably not a lot - you've probably put it out of mind, and are more focused on the car you did buy, or are excited about the car you're about to look at.

Well, it's the same on the other side of the interviewing table. If, after the interview, we decide that the person isn't the right fit for the job... well... we generally don't give them a lot of thought from that point forward. Why would we? We still have to figure out who we're hiring.

Sending a "Thank you for your time" email is a nice touch, but it's not something I'd really even notice if it didn't come. I definitely wouldn't care all that much for a long email/note from an applicant apologizing - it's fine, I've forgotten about it, and I've got other things I need to focus on now.

So here's what I'd recommend: Go ahead and write the apology letter, but don't send it to the interviewer.

Writing the letter might help you get some closure on what happened, or explore how you were feeling during/after the interview, and help put the experience behind you. And, best yet, it might help you do better at the next interview.