I [21M] have been trying to cut off ties with my only group of friends.

I \[21M\] have been friends with 3 people (let’s call them K, D, and S) since the beginning of my college days. We also established a small firm where we freelanced and did tech-related projects for a handful of clients. We all bonded over tech and have been doing the usual friend-group things like sleepovers and house parties for the first year and a half. We had a very great bond until we had a new addition to this friend group, let’s call him ‘N’. N is a year senior to me and joined our group and the firm as a co-founder because K convinced all of us to let him in as he is more experienced. N and K got together very well, and K became an alcoholic/addict while staying with N. Soon, D also started getting involved with N and became a trio who later ended up keeping the firm while I and S backed out as co-founders. The firm wasn’t doing great, we had no clients no business and all the company funds were spent on partying by the trio. At that time N was also an intern at this one other company where I myself, K, D, and S ended up working full-time.

Over the period of time and due to the pandemic, the trio started hanging out even more while I and S moved away from the city to stay with our family. After the pandemic, I visited the company HQ while K was also visiting. During my stay there, he ended up being super drunk and apologized (which later he had no memory of) for being a bad friend and screwing up the business. I felt a bit sympathetic for him at that time and thought maybe we still had our bond of friendship. After a few days, N, K, and, the girl K was seeing at that time went partying. The girl and N ended up hooking up later and K was very furious when he found that out. But N convinced him that it was just a girl and he can’t be angry at N and destroy their friendship because of her. Idk how and why K was so gullible at that time that he agreed to N. A few weeks after that N, K, D, and S went backpacking without me as I had some family problems of my own at that time. N also somehow ended up getting on S’ good side. So with this, I was the outcast of the group. I started spending even less time with them physically because I absolutely hated the presence of N. N is very irresponsible, money-minded, asshole, manipulative, and an absolute piece of shit. He just has this ability to be very sociable and blends in so well in the crowd that people end up liking him. K even had to end a wonderful relationship with his GF because of N’s influence on him. I always wonder how is he able to make so much damage to people while still being their favorite. I definitely want to get away from this group but since we work in the same place, I don’t know how to do it on a non-professional level (?). The only friend I have apart from this group is my girlfriend, who also sees through N’s manipulative behavior and supports my decision of leaving this group. Please advise me on this, how should I do it.

TL;DR: Want to leave a group of college friends but I also share the same workplace with them and work together on a daily basis.

edit 1: briefer tl;dr
edit 2: P.S sorry for my bad English, it’s not my native language