Hi. I have been aware of my sexual orientation for a long while, and I think it is time to come out. But, I'm scared. I'm trying to come out to my only friend, but I don't know what to do. What if i tell him that I'm Gay (What I believe in this moment) and later found out that I'm Bi or even straight? What if he ends up being homophobic and rejecting me? What if he tells another person, like my parents? There are so many things I fear, or that I'm unsure. Please, I need an advice.
Before telling him, you need to be 100% sure that you can trust him. I don't know how long you've been friends, but you need to be sure that he won't harm you in any way for being gay, bi, or anything. If you're not sure if whether he's homophobic, you could bring up the topic casually, just say something about a gay person or gay people in general and see how he reacts. I'm not too sure about this, but another thing that you can do is to tell him a secret that is not actually a secret (so your safety isn't at risk). Make him swear he won't tell anything, and if you find out he does... well, he's not trustworthy.
If you really trust him, you should go for it. BUT. I would test the waters by bringing up LGBT+ related issues/news, and watching his reaction. That should take care of the "homophobic" part. As for the "I don't know whether I'll change my mind", when you're ready to open up to him, tell him that you're still unsure, that you most likely are gay, and most importantly, that you are definitely not straight, because you have that figured out at least Good luck!