I'm sorry that you are so upset and so depressed and anxious. If you are considering hurting yourself in any way, please get support. Call a suicide hotline or the ER. That's serious. And at that point, we really have to talk about underlying anxiety and depression and that these are things that can be treated. I urge you in the strongest way to take that advice and work on this because your life does matter and no one wants you to hurt yourself.
You had unprotected sex. I understand this is worrisome as that is a risk for HIV, however, an episode of unprotected sex is LOW risk. Less than one percent transmission rate for an episode of unprotected sex. And the person you were with is not a high risk person. They aren't a sex worker and they have had sex recently with only one other person. She maybe cheated on him with one person. While these are risks, it's all LOW. And to you, remember . . . LESS THAN ONE PERCENT. You really need to focus on that. Talk to your doctor. A duo test can be done at 28 days. My guess is that it will be negative. You can do an RNA test sooner if your doctor agrees. But ultimately, you need to work on your mental health concerns. Everyone gets nervous and worried and sad. But when it goes to the level of talking about ending your life, it becomes alarming and you need to reach out for help regarding this. Hang in there. I'd bet my right foot you're negative.
You have quite a few post about hiv and mentioned anxiety and ocd in the past too, so that is not a good combination when you have unprotected sex risk because you just worry so much afterwards. Next time insist the other person test first.
https://
www.medhelp.org/posts/HIV-Prevention/Worried-about-HIV--am-I-at-risk/show/3062306
You can take a duo after 28 days for a conclusive result. There is nothing else to do so talk to your doc about the situation you will be in for the next 4 weeks to see if she can help you deal with it.