Oh my love that sounds really tough!! I'm so sorry you're going through this.
I can only speak from my experience having gone to university with a boyfriend (we moved 5 hours away from each other for uni) and we did break up halfway through the year. If I could go back I probably would have broken up with him before I left because the subconscious need to be 'faithful' to him made me feel nervous about speaking to boys even in social settings where any communication wouldn't have been cheating at all, and also when we broke up he cited that being long-distance was too much for him and he 'needed a girlfriend who was actually there', which, granted, wasn't my favourite thing to hear but I can understand where he was coming from. There was also a lot of concern on my end when he would go days without speaking to me (he was a very heavy drinker) and the amount of stress I felt not knowing what was happening to him (as I wasn't there) made some of my time in first year very challenging, but that was my own personal situation and is very unlikely to become yours. I did, however, feel a responsibility as his girlfriend to take care of him from so far away, which was an impossible battle - as much as I wanted to be there with him when he was ill, I just had to love him from a distance through the phone, and it made me feel like half a girlfriend.
On the other hand, simply because your friend is choosing to go to university single, and my personal experience leans that way and towards a fresh start, I don't know either of you or what your boyfriend is like! There is always the option to go long-distance, and if it works that's great and if not then perhaps it wasn't meant to be. I am by no means a relationship expert, as my ex-boyfriend was my first, and I sympathise with you especially as it's playing on your mind so much. I would lean towards if it's a constant thought of should I/shouldn't I then the doubts are there and not so easy to overcome - that perhaps part of you is considering the 'fresh start' kind of avenue. I can assure you that you will meet all kinds of people at university, but I also understand that he feels safe and reassuring - he's a reminder of home and the life you two have together, rather than being completely untethered in a new place with so many new people. I think it more comes down to whether you want to start university single or if you're willing to put in a considerable amount of effort to make long-distance work while juggling some major new aspects of life (new friends, living away from home, etc) - it is ABSOLUTELY possible, it is just a lot of work that both of you need to put in. And it can absolutely be worth it! There's nothing better than a late-night debrief with someone you love and talking about all the new experiences you're having, and it may well strengthen your bond with new things to talk about!
Take care of yourself my dear, and grab an emergency bar of chocolate <3