I've posted about this a few times because I've had a very positive experience telling a few close friends. I think the most important thing is to have a specific reason for why you're telling someone. This both helps you explain things in a way that will be most effective, and helps them understand where you're coming from and what they can do to support you.
For example, I've told for 3 reasons so far. One was a very close friend soon after I first purchased ABDL diapers, and I told there because I really needed her support at a time when I was anxious and freaking out about whether I was doing something that was okay or not. A second was me sharing with a friend who is transgender in order to help support them (I felt strongly at the time, and was correct, that sharing my own oddness would reassure the person). The third was for a different longterm friend who lives near me and who visits all the time. I told her because I was feeling anxiety and discomfort with her visiting me so frequently that she might find something, and I preferred that she know so I could be more relaxed around her.
So, let's go back to your case, Kieran. You don't have to tell your regular friends if you don't want to tell them. If you're feeling like it's an obligation, or they have some kind of right, or they deserve it, you probably shouldn't tell them. Especially if you feel hesitation about telling, don't do it. If you want to tell someone, think about why like in the examples I gave. It's a different kind of confiding if you're looking for someone who can give you advice and support than it is if you're looking for tolerance or a certain casual acceptance. The reason also changes how much you share. If you just want a friend to know so that you can relax around them, you don't have to do more than 30 seconds of telling them that you've got an unusual interest and want to let them know so you can relax and they're not surprised later. If you want support from someone, on the other hand, you need to tell them enough info for them to understand why you're suffering in some way and how they can help.