Hi, English isn't my first language! I hope this all makes sense. I (27f) am friends with M (25FTM) and K (25M diagnosed with autism).

M and K had been in a relationship for almost 10 years until they broke up a few months ago because M, after opening  the relationship, met another guy, let's call him W (23M), with whom he wanted to be exclusive. This whole situation, as you can imagine, was quite complicated, and I'll try to summarize it as clearly as possible.

M and K met when they were teenagers and went through K's autism diagnosis together. K is a fairly functional person, although he has difficulties, especially understanding social norms. He refuses to use smartphones and communicates using his partner's social media accounts. M is a neurotypical person, and you could say they formed some kind of symbiosis. They considered themselves one person, and this caused problems when it came to making friends because, for example, if you wanted to tell M something private, K would end up finding out too. Sometimes M has been offered a job, and K has gone instead to the interviews (where he's been asked to leave). There was a time when I shared an apartment with them, and they wanted to pay a single rent for two people living there (in addition to other living arrangements that I won't go into detail about now). Their main source of income was K's parents, both of whom were really well-off healthcare workers, since they haven't been able to find a job yet.

They maintained this symbiosis until a year ago, when M asked K to open up the relationship so he could explore his sexuality more and date a mutual friend named W.

K accepted, but wasn't comfortable with it and resorted to self-harm and stopped eating. He told me he had constant nightmares about M having sex with W and that he felt inadequate and only a source of unhappiness for M. M, meanwhile, clung to the fact that K had agreed to open it and didn't act on it for almost six months. Throughout this process, M felt guilty about leaving K alone when he traveled to another country to meet with his other partner, and asked me to "keep an eye on K" because he was afraid he might commit suicide. I tried to reason with M a thousand times, saying that if he had that fear, he might as well work things out with K before even traveling because he would also be giving me responsibility for K's mental health. During this time, I had almost no free time to see my own partner because I was studying for my country's equivalent of the USMLE and had to take care of my parents, but I still kept an eye on K because I ended up feeling responsible for him not attempting suicide. M finally broke up with K in January of this year because they both reached a point where they were both acting very toxic toward each other. Shortly after the breakup, M wanted to talk to me because he felt he was resentful towards me because he didn't feel I was supportive enough of their relationship, and he wanted to clear some stuff about how things had been with K. He confessed to me that K had been controlling all these years, that he felt he lacked privacy, and that he lived for him and his routines. He was K´s means of communication with the world and that his in-laws were constantly transphobic toward him, and that K once saw him talking to another guy at university and tried to commit suicide that same day.

I haven't wanted to take sides with either of them because, despite the complicated situation that has dragged on for so many years, I'll never fully understand it. They've both participated in a dysfunctional dynamic, and I'm willing to support both of them as a friend, but outside of the whole relationship thing.

The problem starts when I notice that K has been depending on me a lot lately. We've been communicating via email occasionally, but K has a habit of showing up at my house unannounced. And if no one's there, he'll wait at the entrance of the building for hours. I've explained to him many times that he should give notice in advance  so that the people he's visiting can welcome him without any problems. Each time, he tells me that he understands, but that he simply doesn't intend to come inside the house, just to say hello.

It's gotten to the point where he even stops by my mother's workplace if I'm not home. My parents are very scared, although they also feel sorry for him because they once saw him having a meltdown and with self-harm wounds on his face, and they get tense when the doorbell rings.

 Also, from what M has told me, K is visiting other friends' houses, saying he's a rapist and an abuser.

 As a friend, I'm worried, and I don't mind meeting up with him at an agreed time and place, but I feel like this whole situation, since the breakup with M, has weighed too heavily on me, and I need a break from both of them. I've been taking the USMLE of my country for two years in a row, and I've put a lot of things in my life aside so I can focus. I feel selfish, but now that K is receiving psychological and psychiatric care, I'd like to ignore him for a while so I can rest and focus on myself (also M is living now in another country). I know many of you will tell me that I should set boundaries with them, but either they didn't respect them or I was afraid of triggering self-harm.

AITAH?